According to my calculations and estimations [BB + US + WW]..
#10 - Christina Aguilera
#9 - Shakira
#8 - Beyonce Knowles
#7 - Avril Lavigne
#6 - Madonna
#5 - Mariah Carey
#4 - 50 Cent
#3 - Usher
Album sales: 4.3 + 10 + 1.2 = 15.5
Worldwide sales: 8 + 20 + 2 = 30
#1s: 7
Top 40: 13
TOTAL: 15.5 + 30 + 7 + 13 =
65.5
#2 - Britney Spears
Album sales: 10.5 + 5 + 3 + 1 + 2 + 2 = 23.5
Worldwide sales: 17 + 9 + 7 + 2.1 + 3 + 5 = 43.1
#1s: 1
Top 40: 12
TOTAL: 23.5 + 43.1 + 1 + 12 =
79.6
#1 - Eminem
Album sales: 10 + 10 + 5 + 3 = 28
Worldwide sales: 19 + 19 + 11 + 5.5 = 54.5
#1s: 2
Top 40: 14
TOTAL: 28 + 54.5 + 2 + 14 =
98.5
#4 - #10 weak points: Shakira and Aguilera's overall numbers weren't big enough, Beyonce's worldwide sales were pathetic, Avril's Billboard chartings were poor, Mariah and Madonna's U.S. sales were terrible, 50 Cent's worldwide sales + Number ones were just behind Usher.
So yeah, Eminem just owned this decade and he will own it even further with the new album, while Britney is certainly the female artist of the decade.