The main population centres are on the island of Rarotonga (14,153 as of 2006), where there is an international airport. There is also a much larger population of Cook Islanders in New Zealand, particularly the North Island. In the 2006 census, 58,008 self-identified as being of ethnic Cook Island Māori descent. - With over 90,000 visitors travelling to the islands in 2006, tourism is the country's number one industry, and the leading element of the economy, far ahead of offshore banking, pearls, marine and fruit exports. Defence is the responsibility of New Zealand, in consultation with the Cook Islands and at its request. In recent times, the Cook Islands have adopted an increasingly independent foreign policy. Cook Islanders are nationals of New Zealand: there is no "Cook Islands citizenship".