The following figures had been taken from the BMW Press release in the first half of 2007, they apply to the end of 2006:
R 65 GS: 1,727
R 80 G/S: 21,864
R 80 GS: 7,949
R 80 GS Paris-Dakar: 431
R 100 GS: 22,093
R 100 GS Paris-Dakar: 11,914
R 80 GS Basic: 3,003
R 850 GS: 2,242
R 1100GS: 80,139
R 1150 GS: 21,512
R 1150 GS Adventure: 17,828
R 1200 GS: 82,237
R 1200 GS Adventure: 14,615
source: MOTORRAD ONLINE
All together 287,554 GS's. As far as I know, in 2011 the R 1200 GS / ADV produced since end of 2003 is not far off beating this figure. In 2010 a BMW press release said the R 1200 GS is by far the most successful BMW motorcycle ever, and world wide the most sold motorcycle above 500 cc,
clicky.