Album sales are driven largely by demographics. Adele is selling b/c she has a huge fan base over 30 (and even over 40) years old.

If you think this is crap, here are two words for you - Susan Boyle. Her albums sold millions each time w/o any hit singles, just based on her popularity from her appearances on Britain's Got Talent and the fact that she's adored by older demographics.

The older a person is, the more likely he or she is to still be buying CDs. Teens and 20-somethings rarely buy CDs, and in fact, usually download their music. This has lead to the trend of a new album coming out and seeing several of its songs debut on the chart at the same time. It's b/c listeners actually listen to the album and then just buy the cuts they like.

So, Katy Perry and Rihanna can blow up the singles charts all they want, but their young fan bases will never buy their albums in large quantities.