Here in the UK I have about two dozen 4/8 and 8/8 IPs or sub-ranges banned. Total level3 IP ranges banned (eg as servers) is about 30 and another ten or so IPs blocked other than the 4 and 8 ranges. Not really a big deal and as far as I know my customers get a fair number of legit hits from level3.
On the other hand I have well over 1000 comcast user IPs logged as blocked and about 400 roadrunner IPs (most have since been re-opened: these figures are total IPs blocked in the past couple of years). This compares with approx 1100 UK BT IPs blocked over the same period (most of my sites are mainly UK audience).
Balanced against that is a predominance of US and CA server farms being ill-used, probably more than RU and UA put together as far as my sites see it.
My rough analysis of the blocked IPs is: they were either used by botnets or by ambitious idiots who have no idea what they are doing.