19141 PMs
9791 PM sent
21124 posts

.906 PMs for every post.
.464 PMs sent for every post.

Over five years, this is 346 posts per month, 11.5 posts per day.
Over five years, this is 5.4 PMs sent per day. However, it's important to remember that my PM count has only gone up by about 1000 in the last year and a half. The mass majority of my PMs were sent in a one year period from august 2005 to august 2006. Assuming half of my PMs were sent in that time, that becomes 13.4 PMs per day.