UPDATE: After we published this story, we became aware of two more governors who experienced sex scandals during the time period we were looking at. They are Washington state Democrat Mike Lowry (in a scandal that lasted between 1995 and 1996) and Kentucky Democrat Paul Patton (in a scandal that lasted between 2002 and 2003).

As the nation's governors gather in Washington this weekend for their annual winter meeting, there will be at least one thing missing: a governor saddled with either legal troubles or a sexual scandal.

The numbers are striking: There were no significant gubernatorial scandals known to the public during 2011, 2012 and, so far, 2013. This is the first time the number has been zero since 1998 and 1999, almost a decade and a half ago.

By contrast, between 2002 and 2010 there were always at least two gubernatorial scandals percolating at any given time, peaking in 2004 with four governors simultaneously facing ethical troubles. Prior to that, there was always at least one scandal ongoing as far back as 1995, the earliest year I checked.

Most of these scandals involved investigations into and often convictions related to ethical or legal violations. Five involved sex, and at least two had elements of both.

Before I go any further, let's get some caveats out of the way. First, it's possible that a scandal may be brewing and we just don't know it yet. Second, scandals have recently hit lower-level state officials, such as Dustin McDaniel, the Arkansas Democratic attorney general, and Rick Sheehy, the Nebraska Republican lieutenant governor. (They were both were caught in inappropriate relationships with women.) And third, the recent plea bargain by former U.S. Rep. Jesse Jackson Jr. of Illinois shows that ethical troubles in other levels of government, such as Congress, never really went away.

Now, the closest thing to a current scandal that I could find was an ethics investigation into Republican Gov. Nikki Haley of South Carolina. The alleged violations happened while she was a state legislator and have already been cleared twice by the House Ethics Committee, which suggests that her case -- at least for now -- isn't really that serious.

So what does count? There is no official way to categorize what is and what isn't a scandal, but here is the criteria I used: I only counted cases in which a governor's troubles became publicly known while he or she was still in office. For example, former North Carolina Democratic Gov. Mike Easley was convicted of a campaign finance felony in 2010, but the conviction emerged only after he was term-limited out of office -- so, I'm not counting it.

The count would have been higher had I not chosen to exclude a few other governors whose administrations faced ethical or legal controversies but were either cleared or never directly charged. These include Republican Judy Martz of Montana, Republican Frank Murkowski of Alaska, Democrat Bill Richardson of New Mexico, Democrat Jim Doyle of Wisconsin and Republican Matt Blunt of Missouri.

In measuring how long a governor's scandal lasted, I started the count when serious questions began being aired publicly, and I stopped counting when they left office, even if their troubles persisted after their departure.

Here's a rundown of the governors I included in my calculations, listed in order of year elected and with my best approximation of the dates during which the scandals were publicly known:

Elected 1990

Arizona Republican J. Fife Symington was convicted of seven felony counts of fraud in 1997 and resigned office. His conviction was later overturned and Symington was pardoned by President Bill Clinton. (Duration of scandal: 1996-97)

Elected 1991

Democrat Edwin Edwards of Louisiana went to prison in 2002 for bribery related to casino licenses. (Duration of scandal: 1995)

Elected 1992

Democrat Mike Lowry of Washington state settled a sexual harassment claim by a former aide, denying wrongdoing but paying the plaintiff $97,500 and agreeing to sexual harassment training sessions. He declined to seek a new term after the revelations. (Duration of scandal: 1995-1996)

Elected 1994

Arkansas Democrat Jim Guy Tucker was convicted in 1996 of charges related to the Whitewater scandal and resigned office. (Duration of scandal: 1996)

Connecticut Republican John Rowland pled guilty in 2004 to corruption-related charges and resigned office. (Duration of scandal: 2003-2004)

Kentucky Democrat Paul Patton admitted to an improper role in promoting an employee at the request of Tina Conner, a woman he was having a relationship with. Ultimately, he admitted to two violations, paid a $5,000 fine and faced a public reprimand. (Duration of scandal: 2002-2003)

Elected 1998

Republican George Ryan of Illinois was convicted in 2006 for corruption-related charges. (Duration of scandal: 2000-2002)

Ohio Republican Bob Taft pleaded no contest to violating state ethics laws in 2005. He remained in office. (Duration of scandal: 2005-2006)

Elected 2000

Democrat Bob Wise of West Virginia acknowledged an affair in 2003 and announced he would not seek re-election the following year. (Duration of scandal: 2003-2004)

Elected 2001

Democrat Jim McGreevey of New Jersey acknowledged an affair with a male former appointee who claimed sexual harrassment. He resigned his office. (Duration of scandal: 2004)

Elected 2002

Illinois' Rod Blagojevich, after years of investigations, was impeached in 2009 and convicted of corruption-related charges in 2010 and 2011. The Democrat is currently serving a 14-year prison sentence. (Duration of scandal: 2004-2009)

South Carolina Republican Mark Sanford disappeared from the state in 2009, first telling reporters he was hiking the Appalachian Trail. After his return, it was discovered he was having an extramarital affair and had traveled to Argentina to see the woman. Ultimately, Sanford was censured by the state legislature. (Duration of scandal: 2009-2010)

Elected 2003

Republican Ernie Fletcher of Kentucky was investigated for subverting the state's hiring system; after being indicted, he reached an agreement with the state attorney general that resulted in the charges being thrown out. (Duration of scandal: 2005-2007)

Elected 2006

Nevada Republican Jim Gibbons experienced several controversies starting from the day he was elected, including allegations of sexual assault (which resulted in no criminal charges) and a gifts-for-contracts scheme (for which he was cleared by the Justice Department in 2008). He also was found to have exchanged hundreds of texts on a state cellphone with a woman who was not his wife; this became a factor in a messy divorce. (Duration of scandal: 2007-2010)

Democrat Eliot Spitzer of New York resigned after acknowledging that he had been seeing a prostitute. (Duration of scandal: 2008)

Since 2010, it has been dead quiet on the scandal front. How can that be? I've come up with a few possible theories.

Most of them are freshmen. The 2010 election brought lots of newcomers to the governorship. With only two years under their belts, they haven't had much time to turn bad. However, this doesn't explain everything: Other governors today have been in office for longer without getting into trouble, and earlier governors, such as Tucker, Blagojevich, Fletcher, Gibbons and Spitzer, managed to get into hot water within their first two years.

The Great Recession. The disappearance of fat state budgets has made it harder for governors to skim a little for themselves. Meanwhile, economically pinched voters are less likely to tolerate corruption. "The public has less tolerance than it once did for misbehavior by elected officials," said Martha Joynt Kumar, a political scientist at Towson University.

Rise of the ideologues. Politicians today seem less likely to view government as a source of spoils and more likely to see it as something that needs to be forcibly restrained. This is particularly true for Tea Party-aligned governors, such as Florida's Rick Scott and Kansas' Sam Brownback. Just consider Louisiana: The state once led by Edwards is now governed by an uber-nerdy technocrat, Republican Bobby Jindal.

Gun-shy politicians. The most recent generation of governors may have been scared straight by the political scandals of the past two decades. "You're looking at a generation of elected officials who have come up seeing the hyper-coverage of men and women in the public eye," said Ben Cannatti, a Republican strategist who specializes in state politics. "That level of scrutiny, seen repeatedly year in and year out, heightens awareness of what's illegal, unethical or just downright foolish behavior."

A heightened framework of ethics laws. Once, there was enough vagueness in the law to tempt politicians into questionable behavior. Now there are so many laws and requirements that there are fewer loopholes to exploit and a greater risk of getting caught, experts say. "I do not believe public officials are more or less ethical than previous ages, but there are geometrically more statutes and rules to ensnare them," said Stan Brand, a Washington, D.C.-based attorney who specializes in public corruption cases.

Changes in the media landscape. This factor may be the most intriguing, because it can cut both ways. On the one hand, "the number of statehouse reporters has decreased dramatically over the past few years," said Richard A. Lee, an assistant professor at St. Bonaventure University who previously worked as a statehouse reporter in New Jersey. "Fewer news organizations have statehouse bureaus. The presence of veteran reporters has diminished. These were journalists with extensive institutional knowledge, contacts that could be used for aggressive investigative reporting and for mentoring of younger reporters." On the other hand, Lee said, new media players such as bloggers have helped fill the gap. When New Jersey Republican Gov. Chris Christie was caught using a state helicopter to attend one of his son's high school baseball games, a move for which he later reimbursed the state, the story was broken by an AOL Patch reporter. "In the current media environment, it is extremely difficult for any activity to fall under the radar," Lee said. "Today's journalists have more -- and better -- tools and resources to do their jobs."

And this may mean, among other things, that our current scandal-free era may not last forever.