Tourism at the Vermeer Mill and Historical Village in Pella was up during this year’s Knoxville Nationals. That’s according to Director Bonnie Verberg who says the number of visitors to the popular Pella destination increased by twenty percent from last year during the week before and week of the 2009 SuperClean Knoxville Nationals. Verberg added that though better than last year’s numbers, the attendance was about equal to what they experienced in 2007. Verberg attributes the dip in 2008 to high gas prices and uncertainty about the economy.