Psh, y'all need to save your "It leaked over a year ago!!" rubbish. E.T. leaked a year before it was released, and it was a promo single charting at about #40 in August 2010 before eventually being released properly in February 2011 and it's happily sitting at 5x Plat atm. I don't think that Kanye adding a rap onto it would have boosted a song that much, like, what was his last smash single prior to E.T.?
Now, from the above downfalls, this only leaked a year early - no promo single or album track status, and was technically a lead single. E.T. shows that if a song's good enough, it doesn't matter how long ago it leaked - if it was gonna be a hit, it'll still be a hit.
But well done to Part of Me. Now Katy, I'mma need Thinking of You performances on the Kids Choice Awards and American Idol. Perhaps release a new video too, get that 11th consecutive Top 10 and 11th Platinum single!
(old songs are allowed to re-chart now, yeah?)
It's not that important.