More than 50m digital albums have been sold in the UK

"It has taken just under four and half years for digital album sales to surpass the 50 million figure, whereas it took five years, for the sales of albums on CD to reach the same level.
The new figures released by the recording industry body, the BPI and the Official Charts Company, and shown first to The Telegraph, also show that the 500 millionth single download was purchased in the UK last week.
In 2006, downloaded albums accounted for less than 2% of the UK music industry’s total revenue. For 2010 year-to-date, digital sales constitute 19.6% of all albums sold with download sales expected to top 20 million by the end of the year. Five albums have sold over 100,000 digital copies to date this year, with Mumford & Sons’ Sigh No More being the top seller, having sold 131,737 copies."

Source:  Data from the BPI and the Official Charts Company, reported by the Daily Telegraph, 1st October 2010