In reply to Special Delivery.

Rihanna has accomplished alot in short amount of time.
Personally I believe she is more talented when she is "uncut" (no backtrack, no dancers)..
HERE IS A PARTIAL LIST OF BEST SELLING ARTIST:
(Notice: Rihanna is the youngest among the legends)

The Beatles

Elvis Presley

Michael Jackson

Madonna

Mariah Carey

Celine Dion

Whitney Houston

AC/DC

Queen

The Rolling Stones

ABBA

Garth Brooks

Eagles

Rihanna (2005 -PRESENT

U2

Billy Joel

Bruce Springsteen

Barbra Streisand
Metallica

Eminem

Britney Spears

Rod Stewart

Taylor Swift

Bon Jovi

Fleetwood Mac
******************MAJOR ACHIEVEMENT*************