You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Charleston,_South_Carolina

Context:
Africans were brought to Charles Town on the Middle Passage, first as "servants", then as slaves. Ethnic groups transported here included especially Wolof, Yoruba, Fulani, Igbo, Malinke, and other people of the Windward Coast. An estimated 40% of the total 400,000 Africans transported and sold as slaves into North America are estimated to have landed at Sullivan's Island, just off the port of Charles Town; it is described as a "hellish Ellis Island of sorts .... Today nothing commemorates that ugly fact but a simple bench, established by the author Toni Morrison using private funds."

Question:
What percentage of those sold as slaves in North America landed at Sullivan's Island?

40%