From 1680 to 1800, the Atlantic slave trade grew immensely. From about 36,000 persons per year at the beginning of the century, the trade had more than doubled by the 1760s, and it reached a high point of nearly 80,000 per year in the last two decades of the century. Of the six trading regions identified by David Richardson in his study of the volume of the slave trade (Senegambia, Sierra Leone, Gold Coast, Bight of Benin, Bight of Biafra, and West Central Africa), West Central Africa had consistently the largest volume of exports, running between 30 and 45 percent of the overall trade. The Bight of Benin, mainly from the ports around the Kingdom of Dahomey, was the second most important, with nearly 40 percent of all exports in 1700, which declined to just over 10 percent by century's end. The Bight of Biafra, whose export trade grew rapidly during this time, supplying only 6 percent at the start of the period but peaking at nearly 30 percent in the 1780s, was close behind it. Among them, these three regions supplied nearly three-quarters of all the Africans transported across the Atlantic during the eighteenth century to labor in the Americas. Of the remaining areas, Sierra Leone provided more than one-fifth of the exports for a brief period between 1760 and 1780, at other times less than 10 percent; the Gold Coast never supplied more than 15 percent of the exports; and the exports from Senegal exceeded 10 percent only in the 1720s.