The BMW M division reported around 15,000 vehicles last year for total sales. They don't break down production of each model, but they do say that their business is spread across M models, Individual models, M Sport packages, and Driving Experiences. If we assume that the M Sport packages and Individual vehicles are counted by other divisions, then the 15,000 is 1250 M vehicles per month, similar to reported January 2010 sales of 1146 M vehicles. That article talked about how M sales were holding up despite a global slowdown in auto sales, and that fits from these figures.

We know from published BMW figures that the E60 M5 ran at 4100 per year, and the M3 at more than that. We have a figure for the E90 of 32,000 since 2007, a rather imprecise period, so around 8000 - 11,000 per year, which fits with the M5 numbers. If you put in the M6, which I haven't seen figures for, and subtract all these from the 15,000 in 2009, there isn't room for more many X5Ms per year.

Edit: Found the M6 figures in a separate press release. 14,152 in 5 years, so almost 3000 per year.

Standard X5s are not 200,000 per year, closer to 100,000. The plant produced 8800 in October. US sales have been reported at 3000 per month.

Corrections and additions to the numbers are more than welcome.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue