The past six years have been up and down for the Boise Airport heading into the peak travel season. The airport lost about 16 percent of its passengers between May 2008 and May 2009. May traffic hasnt bounced back since. Spokeswoman Patti Miller says its no surprise that May 2013 was a slow month. Airlines arent adding a lot of new flights, not doing anything drastic, in part because of uncertainty about summer fuel prices, she says. June should show some better numbers.