The Homeland Security Department, which includes offices that deal with immigration files, received more than twice as many requests for records â¿¿ 190,589 new requests last year â¿¿ as any other agency, and it answered significantly more requests than it did in 2011. Other agencies, including the State Department, National Transportation Safety Board and Nuclear Regulatory Commission performed worse last year. The State Department, for example, answered only 57 percent of its requests, down from 75 percent a year earlier.

U.S. Citizenship and Immigration Services drove a dramatic increase in the number of times DHS censored immigration records under exceptions to police files containing personal information and law enforcement techniques. The agency invoked those exemptions more than 136,000 times in 2012, compared with more than 75,000 a year earlier. Even though USCIS is not a law-enforcement agency, officials used the exceptions specifically reserved for law enforcement.

Under the law, a citizen can ask the government to reconsider its decision to censor or withhold materials. In the roughly 11,000 such instances last year where that happened, the government prevailed just under half the time. In about 3,400 cases the government turned over at least some additional information. These administrative appeals took about five months each.

The only recourse after such an appeal is an expensive lawsuit or to ask the government's FOIA mediator, the Office of Government Information Services, to intervene.

The AP's analysis also found that the government generally took longer to answer requests. Some agencies, such as the Health and Human Services Department, took less time than the previous year to turn over files. But at the State Department, for example, even urgent requests submitted under a fast-track system covering breaking news or events when a person's life was at stake took an average two years to wait for files.

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