In a note to clients — as reported by “AppleInsider” ( — latest U.S. sales data from NPD suggests Apple’s Mac sales were up “just” 5% year-over-year during the March quarter, a number lower than some have expected.

Investors generally expect Apple sold 4.3 million units during the three-month period, representing a14 % year-over-year increase. Munster says the lower-than-some-expected sales are because Apple hasn’t released any major updates for its MacBook Pro and iMac product lines in over a year — two lines that account for 50% of Mac sales.

Munster expects Apple will report Mac sales in the range of 4.1 million to 4.4 million, representing 9% to 17% year-over-year growth, respectively. However, he expects sales to pick up in the next few months as Apple revs the MacBook Pro, iMac and MacBook Air lines with Intel’s new Ivy Bridge processors.