In Sunday's "The Nation" section of the New York Times (gasp!!) there is a very interesting article on Shooting and Unpredictability titled "A Hail of Bullets, a Heap of Uncertainty" It tracks the 540 shots fired by the NYPD in 2006. The tracking is by distance from the target. For instance, if the distance between the officer and target was up to 6 feet, 252 shots were fired and 107 hits (43%) recorded. As the distance increases the hits recorded obviously decreases.
Anyway the article is probably online and worth a look (if you dare!)
cheers
YD in SC