Cascada Evacuate The Dancefloor

I heard it on the Radio today i had no idea who the group where or the name of the song apparently its Number 1 in the charts

http://www.youtube.com/watch?v=Ak2Bf5i22oI&feature=fvst

The song played after it was Bulletproof which was also Number 1 before Jacko popped his clogs

http://www.youtube.com/watch?v=NQdC7h609k8

Who the **** are the people that buy/download songs like this enough to get them to number 1??