In a note to clients — as reported by “AppleInsider” (, Piper Jaffray analyst Gene Munster says that domestic Mac sales are up 15% year-over-year for April and May.

Munster says Mac sales were up 28% in the April quarter. NPD figures showed Mac sales up just 16% after the first two months of the April quarter.

The latest number, representing both April and May, is also a marked improvement from the April-only numbers previously reported by NPD, says “AppleInsider.” In that data, “the tough comparison from 2010 left Mac sales up just 9% year-over-year,” the article adds.

Citing the latest research from the NPD group, he adds that Mac sales face a favorable comparison in the month of June. In 2010, new MacBook Pros in April led to a 38% year-over-year increase in sales, while a MacBook refresh in May helped push sales up 35% from 2009. Mac sales should get a boost from 2011 MacBook Pro and iMac updates.