I have been keeping records of my clients since I started teaching a few years ago.  I was playing with excel and came up with some interesting statistics:

Total number of students across all lessons: 1034 (includes recurrant clients)
Average clients per month 64.6
Average lessons per month since august: 55.5 (more individual lessons)
Accidents per hour: 2.23%
Accidents per client: 1.16% (basicly, one in a hundred riders fall off)
Amount of lessons taught: 692

I hate it when people fall off.  Pretty happy with that accident percentage :>