Seasonally adjusted flow from BEA, NIPA, Table 1.5.5, line 46, Imports. Prior to 2007, unadjusted flow from BEA, NIPA, Table 8.1, line 17, Imports. 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.
