HumBio (Human Biology) for quite a few years and I think before that, it was either International Relations or Economics. HumBio is really popular because of pre-meds and other people who want to get into bio-related jobs/grad programs.
HumBio also tended to be the major of no major, the major people declared and the classes they took when they were required to declare a major but hadn't yet figured out what they wanted to major in. The first couple of years of classes were considered relatively easy yet still mostly applicable to many other majors.
