For a period between November 18th and December 22nd, MacBook sales came in 6 percent lower year-over-year, according to new NPD Group data. It's not clear why MacBook sales suffered, although there are several potential reasons. The major driver may be that Apple released only one updated MacBook in late 2012, the 13-inch Retina MacBook Pro; every other MacBook was updated earlier in the year. In late 2011, the entire MacBook Pro lineup was refreshed.
