In reply to christinastherealtalent.

Adele is a huge exception - an anomaly. This is no longer an album market, it's a singles market. Folks simply don't buy albums the way they used to any more. Had Rihanna (the artiste we see now) been around during the Christina/Britney heyday she would've racked up 9.8 million PER album. So to compare her to the likes of Christina and Britney who were really pre-iTunes Let's-buy-cd's-at-HMV artistes is ridiculous. In an era where it's all about singles and music piracy and free downloads, Rihanna is in fact the highest selling female singles vocalist EVER, no small feat. Her sell out tours and airplay paint the real picture.
PS: Rihanna may not have the strongest voice, but she certainly has a distinctive and edgy one, which makes every track she puts out hotter than all of your "proper" singers.