I wanted to do this and sure enough I caught it on the right day. Looks like my first request was sent out 1 year ago, 3/25/09. Actually I sent two requests that day, Dennis Eckersley and Dennis Martinez (got Martinez back)... anyway, here are my rough stats so far. My spreadsheet sort of accounts for duals and multiple requests but not very well.
Sent: 185
Mail Successes: 76
Success rate 41.08%
Average duration of successes 58 days
Failures (RTS): 10
Deceased players: 5
Total cards obtained 85/264 = 32.95% (264 includes deceased and checklists)
Sent: 185
Mail Successes: 76
Success rate 41.08%
Average duration of successes 58 days
Failures (RTS): 10
Deceased players: 5
Total cards obtained 85/264 = 32.95% (264 includes deceased and checklists)