The import column of the input-output (I-O) “use” table shows total U.S. demand for imported goods and services. The import matrix shows the value of imports purchased for final use and for intermediate use by industries for each of these commodities. The import matrix may help users assess how an industry’s use of imports in production affects its output and profits.
BEA produces import matrixes that correspond with the benchmark and annual I-O tables. Because source data are not available that show the imported share of intermediate inputs by industry, the estimates must be imputed from data available in the I-O accounts. These imputed-import values are based on the assumption that the imported share of an industry’s use of a commodity is proportional to the ratio of total imports-to-domestic supply for that commodity /1/. Consequently, annual changes in an industry’s use of imports of a commodity are not based on industry-specific source data, but on changes in the industry’s total use of the commodity and changes in the imported share of the overall domestic supply of the commodity.
/1/ Domestic supply represents the total amount of a commodity available for consumption within the United States; it equals domestic output, plus imports, less exports, less change in inventories.
You can find the import-matrixes in the Industry Supplemental Estimate Tables here.