The historic flooding that devastated south Louisiana will cost the U.S. economy an estimated $10 billion to $15 billion, while public and private insured losses will likely be less than $5 billion, according to global reinsurance broker Aon Benfield.

As many as 110,000 homes and more than 100,000 vehicles were damaged in Louisiana, according to the Global Catastrophe Recap, a monthly report by Impact Forecasting, Aon Benfield's catastrophe model development team. The report used Gov. John Bel Edwards' estimates of homes damaged while the auto numbers came from the National Insurance Crime Bureau.

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A house and car sits in the water in a driving rainstorm off Airline Hwy in Sorrento, La., during Ascension Parish flooding and cleanup on Thurssday August 18, 2016.

Less than 20 percent of the homes damaged were covered by flood insurance, leading to "a substantial disparity" between the overall economic cost and the portion covered by the National Flood Insurance Program, said Steven Bowen, Impact Forecasting director and meteorologist.

"To put the anticipated NFIP losses in perspective, there have only been six natural disasters since 1978 that have resulted in more than $1 billion in NFIP claims payouts," Bowen said. "All six were hurricanes or tropical storms: HU Katrina (2005), HU Sandy (2012), HU Ike (2008), HU Ivan (2004), TS Allison (2001), HU Irene (2011). This is very likely going to be the seventh."

Bowen said Impact Forecasting does not have a good grasp on the number of commercial properties damaged by flooding or whose business was interrupted, but it is extensive.