Seasonally adjusted flow from BEA, NIPA, Table 3.2, line 11, Contributions for government social insurance. Unadjusted flow from BEA, NIPA, Table 3.22, line 7, Contributions for government social insurance. Seasonal factors are calculated as the seasonally adjusted flow at an annual rate, divided by four, less the unadjusted quarterly flow. Series has no levels.