Katy Perry's role as one of our generation's biggest hitmakers is indisputable. She's spent as much time at Number One as Janet Jackson, she's one chart-topper away from Stevie Wonder's numbers, only Michael Jackson can release a single album with as many summit-climbing hits as Teenage Dream, she's the only artist in history to spend an entire calendar year in the Top 10. In honor of her third Rolling Stone cover, here's a rundown of the 20 biggest hits that got her there.