Dr. Dre earned $620 million last year, but this year Diddy, Jay Z, and Drake all surpassed him

Last year, Dr. Dre made the most money in hip-hop after Apple purchased his company, Beats Electronics, for $3 billion. A year later, Dre has slid into fourth place behind Diddy, Jay Z, and Drake.

According to Forbes, after coming off the big $620 million personal payday from Apple, Dre's checks have shrunk a bit, essentially reducing his cash flow. Dre is still massively rich, regardless.

Aside from his newfound wealth via Apple, Dre executive produced the N.W.A. biopic "Straight Outta Compton," (which has netted about $160 million in the US to date) and released an album that coincided with the film. Those numbers, however, weren't factored into the current rankings.

With Dre's fall, Diddy moved right into the first spot, even though he rarely ever performs or makes music anymore. He's all about business, and it's paying off.

Jay Z - to the surprise of no one - moved up a spot as well, to No. 2. The rap mogul simply knows how to make money. Leading the charge for Jay is his Roc Nation music label. Roc Nation also has a sports division that contributes to Jay Z's earnings. Though Jay Z's newest business - the music streaming service, Tidal - has been hammered by rumors of an imminent demise, it has remained afloat thus far.

The biggest surprise perhaps was rapper Drake coming in at No. 3 - the highest ranking he's achieved in his young career. Drake was fourth last year, but after selling over a million copies of his "If You're Reading This It's Too Late" album released in February, the "Trophies" rapper moved into the upper echelon.

Check out the entire list below, complete with how much each artist made over the past year.