Denver International Airport’s popularity soared in 2017 with the airport hitting record highs. Of the 100 busiest travel days in DIA’s 22-year history, 76 happened this year. There’s a simple reason for that, airport officials said. “A lot more people start and end trips here because there’s a lot more people living here,” said Patrick Heck, DIA’s chief commercial officer, who oversees revenue. DIA’s traffic is mimicking the growth of the region, which helped the state rank seventh highest for growth rates nationwide last year.