According to new third quarter figures issued by market research firm NPD Group, Apple’s iTunes music store now accounts for 66.2% of online music purchases, up from 63.2% in the same quarter last year. Apple’s biggest competitor in the space, Amazon, currently holds 13.3% of the market. Executives from major labels suggest the disparity could be even larger, with Amazon owning just 6% to 10% of the market while Apple’s share is nearly 90%. Pricing, often a major factor in retail sales, does not appear to have a major impact on digital music sales. Amazon’s strategy, beyond various distribution deals, is to undercut iTunes. Amazon’s average selling price for popular albums is significantly lower than the $9.99 to $14.99 Apple often charges, and even deeper discounts can be found regularly through promotions like “Daily Deals.” Despite Amazon’s best efforts, however, iTunes’ digital market share continues to grow and Apple’s service remains the global leader in music sales, having surpassed Walmart to take the No. 1 spot in 2008.