From BMW Group PressClub USA:

MINI USA reported sales of 4,320 automobiles in December, an increase of 23.8 percent from the 3,489 in December 2009, making it the most successful December ever for MINI in the USA.  For the year 2010, MINI reported sales of 45,644, an increase of 0.9 percent from the 45,225 sold in 2009.

December 2010 December 2009 change year 2010 year 2009 change
4,320 3,489 23.8% 45,644 45,225 0.9%

See MINI sales in the USA by month.