Greater numbers of high-school students are taking Advanced Placement (AP) examinations and are faring better on them than in the past, said a report released by the College Board. The board, a nonprofit association, administers 37 AP exams, which allow high-school students to earn college credit or exemption from introductory-level college classes. The tests are graded on a scale of 1 to 5, with 3 the minimum score required to demonstrate college-level competence in a particular subject. The total number of students taking AP exams increased by 9.7 percent in 2006 over the previous year, the board said. It reported that 14.8 percent of the 2.7 million students who graduated from public high schools in 2006 earned AP-exam scores of 3 or higher in high school. That proportion is up from 14.1 percent in 2005 and is considerably higher than in 2000, when 10.2 percent of those graduates had scores of 3 or higher. The report, "Advanced Placement Report to the Nation 2007," also highlights the results of two new studies that linked AP preparation to success in college.