Hi TD. I'm not positive, but I'm pretty sure that would be "once every fifteen years per aircraft," or about once every 50,000 flight hours, as opposed to once every 50,000,000 hours if it was once every fifteen years for a fleet of 1000 airplanes for strikes near 100kA and above. I could be wrong. I don't know that aspect of the industry data either, but I know someone who does. I'll ask him and report back.