Duluth, Mn (KDAL)  Passenger traffic saw an 8 percent increase for the first three months of 2010 compared to a year ago at the Duluth International Airport.  The growth in the January, February and March figures are attributed to new service by United Airlines to Chicago and by Allegiant Airlines to Orlando.  Airport Executive Director, Brian Ryks, says it's critical that consumers continue to support the flight options that are available in Duluth.  He says the healthy competition between multiple airlines leads to more competitive airfares and better service.