Every hopeful immigrant knows that there are constraints on the availability and issuance of United States Green Cards.  The limited availability of U.S. visa creates the main backlog on green card applications.  Employment-based green cards for foreign workers and their families are also limited by the United States government, and the 2015 cap has been set at 144,000 per year, world-wide.  Family-sponsored preference categories for 2015 are limited to 226,000 visas per year.  USCIS also places a total annual cap on the amount of visas that can be issued to foreign nationals from any particular country.  For 2015, no country can receive more than 7 percent of the total annual number of family-sponsored and employment-based visas or approximately 25,600 visas.