Fairfax County and Alexandria students are taking and passing more Advanced Placement exams, a benchmark of college readiness, according to data released by the school systems Wednesday.

More than 16,000 Fairfax County high school students took 35,759 of these college-level tests last spring, a 5 percent increase over 2011. The percentage of exams receiving a passing score increased from 69 percent in 2011 to 72 percent in 2012, with gains made by every racial subgroup.

On Alexandria's much smaller scale -- the district claims just one high school, T.C. Williams -- achievement also went up, "besting the historic levels seen in recent years," spokeswoman Kelly Alexander said. A total of 785 students took 1,623 AP exams, a 4 percent increase over 2011. About 59 percent of these tests earned a passing grade, a 3 percentage point increase.

Fairfax results
2009 2010 2011 2012
Number of students tested 14,835 15,439 16,162 16,356
Number of AP exams passed 21,134 22,592 23,613 25,644
Percent of exams passed 71% 70% 69% 72%
Mean score (out of 5; 3 is passing) 3.27 3.26 3.25 3.31
Source: Fairfax County Public Schools

Arlington County is expected to release its students' results in February.

In Fairfax, Superintendent Jack Dale said his district was working hard to expand access to advanced coursework to all students.

Steven Greenburg, president of the Fairfax County Federation of Teachers, said the results "amazed" him.

"It's amazing considering all of the demands that are put on parents and teachers and students. It's amazing that our students continue to improve and accomplish at the level they do," he said.

While more Fairfax County students also took International Baccalaureate tests, offered at eight of 25 high schools, the number of exams receiving a passing score dipped slightly from 74 percent to 72 percent. Dale characterized this fluctuation as "relatively stable."

The achievement gap between African-American and Hispanic students and their typically higher-performing white and Asian peers remained largely unmoved in this year's results, although every group made gains. Fifty-one percent of exams taken by African-American students received passing grades, up from 48 percent in 2011, while Hispanic students' pass rate nudged up from 60 to 61 percent. White students passed 75 percent of the exams, a 2 percentage point increase, while Asian students passed 72 percent of AP exams they took, up from 68 percent.

Last week, officials in Montgomery and Prince George's counties revealed that their students' participation and pass rates had increased since 2011. Montgomery County Public Schools claimed the highest success rate in the region in 2012, with 75 percent of exams receiving a passing score. Prince George's students had a 27.2 percent pass rate, up approximately 10 percent from a year ago.