Import product concentration index

This indicator reflects the Herfindahl-Hirschmann index measure of the degree of import concentration within a country. The sectoral Hirschmann index is defined as the square root of the sum of the squared shares of exports of each industry in total exports for the region under study. Takes a value between 0 and 1, with 1 indicating that only a single product is exported. Higher values indicate that imports are concentrated in fewer sectors. On the contrary, values closer to 0 reflect a more equal distribution of market shares among importers. Note that this type of concentration indicator tends to be quite vulnerable to cyclical fluctuations in relative-prices, in a way that commodity price rises make commodity importers look more concentrated.