Planters were firmly entrenched by 1650's, and the number of slaves imported to work the sugarcane plantations, by now the island's sole industry, greatly outnumbered the whites. The great plantocracies were in the hands of a few wealthy, often absent landowners. In the late 17th and early 18th centuries, slave revolts reverberated throughout the Greater and Lesser Antilles. Barbados saw revolts in 1672, 1696, 1702 and 1816, the latter being the island's largest revolt. Sugar exploitation however prevailed, and so did slavery, until the 1834 abolition. For the remainder of the 19th century, free slaves and their descendants drifted away from the sugarcane fields. Nearly 80% of Barbados's citizens are descendants of African slaves.