Budget cuts. Revenue streams. Demographics. State and local governments operate in a world of numbers. Governing features a Daily Digit every morning to draw attention to a figure that is meaningful for our readers. So, with the end of the year arriving, Governing collected the top 10 Daily Digits from 2011, presented here in reverse chronological order.

327,577: The number of illegal immigrants arrested trying to cross the U.S.-Mexico border in 2011, according to the Washington Post, the lowest number since 1970. The Post reported in December that that figure and other information indicates that Mexican migration into the United States has slowed to historic lows. “We have reached the point where the balance between Mexicans moving to the United States and those returning to Mexico is essentially zero,” Jeffrey Passel, a senior demographer at the Pew Hispanic Center, told the newspaper.

1 in 8: The share of Americans who are now over 65, an all-time high, according to the Christian Science Monitor. As the baby boomer generation continues to age, that number is only expected to increase, the Monitor reported in November. With federal lawmakers looking to reign in the federal budget deficit, entitlement programs for senior citizens such as Social Security and Medicare have come under heavy scrutiny.

More than $3 billion: The amount of debt that Jefferson County, Ala, accumulated because of a corruption-plagued sewer project, according to Bloomberg Businessweek. The county declared municipal bankruptcy in November, the largest in U.S. history, the magazine reported. Harrisburg, Penn., has also garnered headlines for its recent attempts to file for bankruptcy because of ballooning debt.

4,935: The number of Wisconsin teachers who retired in the first half of 2011, according to the Associated Press, twice the number who retired in 2009 and 2010 combined. Some blamed the new state law that restricted collective bargaining rights, the AP reported in September. The law has led to a concerted effort to recall Republican legislators and Gov. Scott Walker who supported it. A similar Ohio law reducing collective bargaining rights was overturned by voters in November.

$40.54: The average hourly cost to employers for a state or local government worker in the first quarter of 2011, according to the Wall Street Journal, compared to $28.10 for a private sector employee. The public sector has taken a hit as budgets have been reduced: about 250,000 state and local government jobs were cut from November 2010 to November 2011, according to data from the Bureau of Labor Statistics.

9.3%: The percentage of state revenue growth in the first three months of 2011, according to the Wall Street Journal, compared to a 0.64% decline for local governments. The Journal reported in June that the difference can be partly attributed to states' dependence on sales and income taxes, which recover more quickly than local property taxes. "States are making their way back, but there's still a lot of uncertainty ahead," Robert Ward, deputy director of the Nelson A. Rockefeller Institute of Government, told the newspaper.

80%: The percentage of public schools that Education Secretary Arne Duncan estimated in June would be classified as failing and face sanctions under No Child Left Behind, according to The New York Times. Bills have been introduced in Congress to reauthorize the law, eliminating the Adequate Yearly Progress system and putting the responsibility for accountability in local control. The Obama administration has also initiated a waiver program for states from the law's requirements, provided they commit to certain reforms.

12%: The portion of Detroit that is empty, totaling more than 100,000 vacant lots, according to the Detroit News. The News reported in April that city officials were considering consolidating the city's diminishing population into a few neighborhoods. The decline has also impacted the city's coffers. Recent analysis by the state has suggested Detroit needs an emergency manager to fix its finances.

69,000: The number of bridges that need major repairs or complete replacement in the United States, according to a Transportation for America report. Reuters reported in March that the American Society of Civil Engineers has estimated that the nation needs to invest $17 billion yearly to improve current bridge conditions.

44.8%: The percentage of American adults who get health insurance through their employers, according to Gallup. The polling group reported in December 2010 that 26 percent of Americans receive health insurance through a government program, and 16 percent do not have any health insurance. This year had states preparing for an influx of Medicaid enrollees under the Affordable Care Act, and they have been tasked with designing health insurance exchanges also mandated under the law.