Leaking music on the internet

So,i have to pay attention to this. As you may notice(or not) these days a lot of songs from upcoming albums by an artists like Ciara,Kelly Clarkson and many others(especially these two) are all over the internet. Im pretty confused who's leaking this stuff and i really want it to stop because it harms albums sales :(

Anyway,those songs are leaking next,apparantly:

Katy Perry - Look Dont Touch
Katy Perry - My boyfriends & Ex Girlfriends
Kelly Rowland - Just Whisper
Katy Perry - Nothing Like The 1st
Katy Perry - Wanna Be
David Guetta ft Akon - Famous
David Aude ft Nicole Scherzinger - Im Gonna
Christina Milian - Version Of Love
Ciara ft T-Pain - We Can Get it On
Christina Aguilera - Kimono Girl
Christina Aguilera - Bionic
Kelly Rowland - The Sound
Leaona Lewis -A Thousand LIghts
Leona Lewis - Burning Down
Leona Lewis - Down
Leona Lewis - Haunted
Leona Lewis -Piece of Your Heart
Leona Lewis - PlayGround
Lil Wayne - Role Model
Mariah Carey - Help Me Make It
Mariah Carey - Imperfect
Mario - Play Hard To Get
Nelly Furtado - Free
Nelly Furtado - I am A Minor
Nelly Furtado - Special
Ne-Yo -I am Not an Idiot
Neyo - No Drama
Ne-Yo -Stronger Now
Ne-Yo - Wake You Up
Nicole Scherzinger - Get Em Ready
Usher - I Did it
Trey Songz - I Cant, I Wont
Usher- Mayday
Usher- U So Fire