Rihanna named No.1 pop star of the decade by Billboard magazine

Billboard ranked the hottest 100 pop stars of the decade based on sales, and Rihanna came out on top. She has the most chart appearances (34), the most top 10s (21) and the most no. 1 hits (9).

See the top 10 below...
1. Rihanna
2. P!nk
3. Britney Spears
4. Kelly Clarkson
5. Mariah Carey
6. Katy Perry
7. Usher
8. The Black Eyed Peas
9. Janet Jackson
10. Madonna