Why Is Everyone Whistling?

I’ve noticed a recent trend in the music industry. Four of Billboard’s top 15 songs feature whistling prominently. Take a look:

Maroon 5 featuring Christina Aguilera – Move Like Jagger (#2)



Foster the People – Pumped Up Kicks (#3) -- (To my knowledge, this band has no relation to former Steelers RB Barry Foster.)



Britney Spears – I Wanna Go (#13)



OneRepublic – Good Life (#15)



This doesn't include Lazy Song by Bruno Mars from earlier this year or last year's The Black Keys hit Tighten Up.

Not to sound like Seinfeld, but what's the deal with all of this whistling?