Since 2000, the number of nonhuman primates held in laboratories has increased from over 95,381 to over 107,125 in 2012, an increase of more than 10%. Nearly 30,000 primates were subjected to painful and distressful experiments in 2012. Although these numbers include chimpanzees, because labs are not required to report specific species numbers, it is difficult to know exactly how many chimpanzees are being used in research. However, macaques are the most commonly used primate species.Macaques also make up the majority of nonhuman primates imported for research. Other highly imported species include marmosets, squirrel monkeys, olive baboons, vervet monkeys, and night monkeys. Many primate populations around the world have been adversely affected, as monkeys are stolen from the wild to be used for research purposes.