Research also finds that migration leads to greater trade in goods and services. Using 130 years of data on historical migrations to the United States, one study finds "that a doubling of the number of residents with ancestry from a given foreign country relative to the mean increases by 4.2 percentage points the probability that at least one local firm invests in that country, and increases by 31% the number of employees at domestic recipients of FDI from that country. The size of these effects increases with the ethnic diversity of the local population, the geographic distance to the origin country, and the ethno-linguistic fractionalization of the origin country."