Believe it or not, we know EXACTLY how many spots were hit last year. We stopped paper charting everything and went to a program called Pitcher's Edge. We chart on a palm pilot and can run a Pitcher Command report.
See if you find this interesting...
19% of our pitches were Hit Spots (catcher didn't move the glove): Out of those, only 2% were put in play hard.
27% of pitches were Slight Misses (not dead on the spot, but close): Of those, 8% were hit hard.
54% of pitches were Major Misses (didn't come close to intended spot) Of those, 17% were put in play hard (if they were swung on).
I agree with Texan that in general, the reality of command is that very often we succeed without hitting our spots. 19% may sound terrible, but our opponents hit their spot 15%, and slight missed 20%.
I learned a lot from this charting experiment and we continue to use the program in bullpens, intrasquads, and games. Our pitchers constantly try to improve their numbers. Pretty cool stuff!