"In the 2005-2006 fiscal year, the county paid $78 million in pension costs for current and former employees. Its contribution almost doubled to $146 million by 2011-2012.... The county's pension contribution likely will increase by an additional $13 million in 2013-2014 ... because the assumed rate of return on its investments was lowered by the San Mateo County Employees' Retirement Association in May from 7.75 percent to 7.5 percent.... [W]hile workers are supposed to pay part of their retirement costs, the county picks up a higher than required share of some employee groups such as management, attorneys and employees with more than 10 years of service. As a result, the county picked up 78 percent of some employees' pension costs in 2010-11 instead of 75 percent."