On or before January 1, 2020, and on or before January 1 of each year thereafter, the department shall compile the results of the radon measurements performed in the past five years that were reported to the department pursuant to the rules and regulations adopted and promulgated by the department regarding the control of radiation and report such compilation electronically to the Clerk of the Legislature. Such report shall determine the average radon concentration in Nebraska by county and identify each county in which such average concentration exceeds two and seven-tenths picocuries per liter of air.