Task: Question Answering
Input (English): Sentence: In September 1695, Captain Henry Every, an English pirate on board the Fancy, reached the Straits of Bab-el-Mandeb, where he teamed up with five other pirate captains to make an attack on the Indian fleet making the annual voyage to Mocha. The Mughal convoy included the treasure-laden Ganj-i-Sawai, reported to be the greatest in the Mughal fleet and the largest ship operational in the Indian Ocean, and its escort, the Fateh Muhammed. They were spotted passing the straits en route to Surat. The pirates gave chase and caught up with Fateh Muhammed some days later, and meeting little resistance, took some £50,000 to £60,000 worth of treasure. 
Question: how often did the Indian fleet voyage to Mocha?
Output (English): annual