Las Vegas convention attendance was up by 4.4 percent in May, compared with a year ago, despite a slight decrease (0.6 percent) in the number of events held, according to numbers recently released by the Las Vegas Convention and Visitors Authority. The attendance boost was due in large part to the rotation into town of the Lightfair International convention, which brought 22,000 attendees. Year-to-date, convention attendance has inched up by 0.1 percent over 2011. Total visitor volume increased by 2.4 percent in May, and is running at a 2.4 percent increase for the year. Average daily rates climbed by 3.7 percent in May, and are running 3.4 percent higher for the year.