Even, in the end of 2008, digital sales in the UK weren't high. I mean look at that, Rihanna sold only 2,5 million singles in 3 years (2005-2008) and she was named the best selling digital artist by Guinness:
So it's not like she had THAT much help from pre-2009. She sold around 9 million singles between 2009-2012.. And look she sold 3 million singles in just 12 months 2011/12 and from 05-08 it took her 3 years to just sell 2,5 million!
Rihanna's sales are impressive!