Mine from the past 3 months have been.
1) Leona Lewis (1402 plays)
2) Taylor Swift (308 plays)
3) Florence + The Machine (256 plays)
4) Ellie Goulding (252 plays)
5) Beyoncé (250 plays)
6) Kei$ha (218 plays)
7) Shakira (211 plays)
8) Katy Perry (203 plays)
9) Alicia Keys (202 plays)
10) Lady Gaga (167 plays)
11) Alexandra Burke (165 plays)
12) Pixie Lott (85 plays)
13) Lily Allen (83 plays)
14) P!nk (50 plays)
15) Rhianna (43 plays)
16) Gabriella Cilimi (42 plays)
17) Diana Vickers (41 plays)
18) Sugababes (41 plays)
19) Miley Cyrus (40 plays)
20) Noisettes (38 plays)
This is according to Last Fm last 3 months
.
I like my top 20
i Have Joe Mcelderry, Jason Derulo, Chipmunk, The Killers and The Black Eyed Peas, Justin Bieber, Calvin Harris, Girls Aloud, JLS and Cheryl Cole as 20-30.