The Federal Reserve Bank of Kansas City tabulated farm exports. These percentages are based upon their estimates for 2011-2020.
The share of the US crops that is exported each year:
Wheat – 46%
Corn – 15%
Rice – 53%
Soybeans – 47%
Cotton – 81%
The US share of total world crop exports:
Wheat – 18%
Corn – 53%
Rice – 11%
Soybeans – 39%
Cotton – 35%
The share of livestock that is exported:
Beef 10%
Pork 22%
Poultry 17%