Average return mail for direct mail & virtual mailboxes

[Michael Merritt]

What's the average amount of return mail you get as a wholesaler that does direct mail? I'm looking into using a virtual mail box and seeing they'll 80-100 pieces of mail then it becomes .35 cents per piece. 

I'd love examples of how much mail you send out and how much returns? I know this depends on what lists and frequency of mailing. Maybe I can stagger my mail blasts so they come back in pieces instead of all in 1 month.