50% is more realistic for 1860.
Your higher number might well be realistic for prior years, but by 1860 other US products, especially manufactured, also were growing rapidly.
BroJoe, as I have told you several times, you are not understanding your own data or correctly using it. You have confused export products, specie, and re-exports while failing to quote the entire export picture. Here is the information on export contributions:................................U. S. Department of Commerce
................................Agricultural Production of the South
........................................Yearly Detail 1859
Value of Total U.S. Exports ..........$278,902,000
Value of Raw Southern Products:
....................Cotton .....................$161,435,000
....................Tobacco .....................21,074,000
....................Rice ............................2,207,000
....................Naval stores .................3,696,000
....................Sugar ..........................197,000
....................Molasses ........................76,000
....................Hemp .............................9,000
....................Other ........................9,615,000
________
Total ( 71% ) $198,309,000
Value of Southern manufactured Cotton exports ............4,989,000
Value of cotton component of Northern Manufactured cotton exports (60%) ......3,669,000
___________
Total ( 74% ) $205,459,000
74%
U.S. Department of Commerce, U. S. Treasury, Report of L. E. Chittenden, Howell Cobb, Treasurer, Annual State of the Union Address, James Buchanan, J. D. B. DeBow, Charles Adams, Thomas Kettel, W. F. Taussig, Thomas Huertas, Historical Statistics of the United States Department of Commerce, pg. 106,432.