The pension funds for USPS workers are purely hypothetical. Within the vast Civil Service Retirement Systems, there is no money specifically segregated for postal workers. The assumption that the securities in the trust fund would earn 5 percent annually on behalf of postal workers was set in 1971, in the legislation authorizing the USPS reorganization, and was never changed. In that regard, the CSRS is much like the Social Security system—funds are paid in to deal with future liabilities, the assets consist largely of government securities, and the returns rest more on legislation and political consideration than market performance.