For statistics, on avg we have 75/d direct attempts of registration where of 5/d actually walk through (even with captcha or question tests) and 3/d do actually post spam. In peaks we have 50/h attempts with about the same ratio. All this is behind the firewall and behind the IP blacklist, without those two we had peaks of 5k/h page request with the same ratio of created accounts and spamposts every couple of months and almost annualy around Sep 30th a very peak (that peak is with delay of 3-5 days hitting TJC in the same manner).