In 1680, the newly formed French East India Company sent a ship to Thailand, bearing a trading mission led by André Deslandes-Boureau, son-in-law of the Governor General of the French settlement in Pondicherry François Martin, which was well received by the Thais. In September 1680, a ship from the French East India Company visited Phuket and left with a full cargo of tin. The Dutch, the English, and from the 1680s the French, competed with each other for trade with the island of Phuket , which was valued as a rich source of tin. In 1681 or 1682, Siamese King Narai, who was seeking to reduce Dutch and English influence, named Governor of Phuket the French medical missionary Brother René Charbonneau, a member of the Siam mission of the Société des Missions Etrangères. Charbonneau held the position of Governor until 1685.
Question: How many years did Charbonneau hold the position of Governor, at most?
Answer: 4