However, "It has recently become clear . . . that these estimations of overall participation rates mask the variability in participation rates across AP examinations." For example, one study of math and science AP courses showed that participation rates were 52.7% for AP Chemistry, 53.6% for AP Physics, 57.7% for AP Biology, and 77.4% for AP Calculus. The largest study on this topic found similar participation rates (49.5% for AP Chemistry, 52.3% for AP Physics, 54.5% for Biology, and 68.9% for Calculus). History exams tend to have slightly higher participation rates (57.9% for AP European History, 58.5% for AP World History, and 62.8% for AP U.S. History), and 65.4% of AP English students took either the AP English Language or AP English Literature exam. This same study found that for "core AP subjects (i.e., no arts or language subjects)", the overall test participation rate was 60.8%.