This end of year article from ComputerWorld offers data on the increasing sale of Chromebooks in 2013.
By NPD’s tallies, Chromebooks accounted for 21% of all U.S. commercial notebook sales in 2013 through November, and 10% of all computers and tablets. Both shares were up massively from 2012; last year, Chromebooks accounted for an almost-invisible two-tenths of one percent of all computer and tablet sales.
ComputerWorld concludes that the increased sales of the Chromebook comes at the expense of computers running the Windows OS.