Based on data from the Pennsylvania Public Employee Retirement Commission (PERC), there were 298 pension plans in Allegheny County in 2011 (most recent audited year). Based on active membership (in aggregate there were more than 18,000) about half of these plans had 10 or fewer members in them that year.
How does that compare statewide? In PERC’s 2011 municipal pension plan report there is a higher percentage of plans (68%) that have 10 or fewer members than in Allegheny County. PERC notes that it uses a threshold of 100 active members to determine whether a plan is "large" (100 or more) or "small" (99 or less) and, by that measure, 98% of local plans in Pennsylvania are considered small. Here the plans in Allegheny County track much closer to that calculation, with 96% of plans having less than 100 members. Only 10 plans have 100 active members or more-all of them are either related to the County or the City of Pittsburgh by being the primary plan of employees or of related authorities.