You had to look hard for those big acts! Why don't you take the hottest performers today and see how that goes. Ill give you a list: Eminem, Katy Perry, Rihanna, Miley Cyrus, Chris Brown, Pitbull, Shakira, Beyoncé, Jay-Z and Justin Bieber. That should get you going for a few hours then we can talk about it!
BTW, it took me 30 seconds to find your source. http://www.stereotude.com/galleries/15-hip-hop-artists-degrees/2042671
I like Ice Cube so I checked out Wikipedia. He was a senior in High School in 1987. How did he get a bachelors degree in 1988? One down, 14 to go. But wait, John Legend is not hip hop. 2 down 13 do go!