LOUISVILLE — Vaisala Inc., a global environmental and industrial measurement company based in Louisville, has released new data calculating the number of lightning strikes in the region and across the United States. Strikes in the United States are among the lowest in the last 10 years, with 17.8 million negative cloud-to-ground flashes (the most common type of lightning) in 2018. This number is down 11 percent from the 10-year average. Colorado had 467,855 strikes. In the region, Weld County had the most strikes, with 38,384 negative cloud-to-ground flash counts. Larimer County had 12,520. Boulder County had 3,207 flash counts, and Broomfield County had just 137, given its smaller size than the other counties. Vaisala’s National Lightning Detection Network is used by U.S. meteorologists and the National Weather Service. The company’s Annual Lightning Report found that the 10-year average for lightning strikes from 2009 to 2018 was 19.7 million flashes. The years 2012 and 2013 were the only years that had a lower number of strikes than 2018. Texas had the highest number of strikes in the United States, while Florida had the highest density. In Colorado, Sedgwick County had the highest strike density, followed by Logan, Yuma, Phillips and Kit Carson Counties.