Read this and answer the question. If the question is unanswerable, say "unanswerable".

The show itself is popular in the Southern United States, with households in the Southeastern United States 10% more likely to watch American Idol during the eighth season in 2009, and those in the East Central region, such as Kentucky, were 16 percent more likely to tune into the series. Data from Nielsen SoundScan, a music-sales tracking service, showed that of the 47 million CDs sold by Idol contestants through January 2010, 85 percent were by contestants with ties to the American South.

How many CDS were sold by Idol contestants up to 2010?
47 million