Apple watcher Gene Munster of Piper Jaffray on Tuesday revealed NPD Group data showing estimated Apple computer shipments in the U.S. for the first month of the company’s 2011 fiscal year. According to NPD Group’s numbers, Mac sales were up 20% year-over-year in January and shipments are on pace to reach 3.6 million units in the quarter. Wall Street is expecting global Mac sales to grow 22% year-over-year, and Munster believes Apple will meet expectations. Conversely, NPD shows that U.S. iPod sales declined 10% in January compared to the same month last year. Apple is expected to unveil a refreshed MacBook Pro line very soon, and strong demand for its popular MacBook Air laptop line should result in strong sales for the remainder of the quarter.