For the fourth year in a row, Singapore Changi Airport has bagged the World’s Best Airports title at the annual SkyTrax World Airport Awards, announced Wednesday in Cologne, Germany. The Skytrax awards are based on millions of votes collected in passenger surveys. Many of those passing through the island city-state are clearly pleased with the airport’s innovations, such as two 24-hour movie theaters screening the latest blockbusters for free, a rooftop swimming pool and a butterfly garden. Coming second is South Korea’s Incheon International Airport, which has held the No. 2 spot since 2013. This year’s top 10 list hasn’t changed much from previous years, though the addition of Doha’s Hamad International Airport, from 22nd place last year, marks the first Middle East airport to join the ranks. Airport authorities in Japan are getting things right, too, with three of its airports among the top 10. Once again, North America failed to have an airport in the top 10. Vancouver International Airport, the No. 1 airport in North America for a record seventh consecutive year, …