CDs account for 76% of album sales in the UK

"While sales may be on the wane – and illegal downloading on the rise – CDs remain the nation's favoured format, accounting for 76.1% of total sales last year, compared with a 23.5% market share for digital and 0.3% for vinyl."

Source:  Data from the BPI, reported by The Guardian, 3rd January 2012
Update - in the US it's 68%