According to the latest data from market research firm NPD, iPod sales grew 11.6 percent year-over-year in May, following growth of 14.6 percent year-over-year in April. In a note, Lehman analyst Tim Luke pointed out that this was well ahead of the 2 percent decline the firm had been expecting, and said that average iPod pricing in the quarter was down 4 percent. “While not exactly strong, iPod demand seems to be holding up and benefiting from the…