Task: Question Answering
Input (English): Passage: In 1718 the Danish claimed the island of St. John to develop sugar plantations and crops such as indigo and cotton; there was especially great demand for sugar and prices were high in Europe. Dutch planters were still important on the island. By mid-1733, planters had developed 109 plantations, and slaveholders owned more than 1,000 African slaves on St. John. One-fifth of the plantations were then devoted to sugar; by the end of the century, most would be, and the total slave population would be 2500. In 1733 the population of African slaves on St. John was more than five times larger than that of the European inhabitants: 1087 slaves and 206 whites. Many of St. John's plantations were owned by people residing on St. Thomas. These absentee landowners hired overseers to manage their lands and slaves on St. John. Under these conditions, overseer cruelty flourished. The Danish West India Company provided only six soldiers for the defense of St. John, which supplemented the local white militia. 
Question: How many years was it between when the Danish claimed St. John to when planters had developed 109 plantations? 
Answer type: Number 
Output (English): 15.