Insurance: We've Passed the Height of the Tornado Season and Are Decisively Below Average (again)

The very good news is the U.S. had the longest fatality-free start to a season in 99 years. This is due to a combination of advances in warnings over the last sixty years and a marked decline in tornadoes over the last few seasons. Here are a couple of the pertinent graphs:
Probability

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Year to date count

(click to enlarge)

Tornado counts are Detrended and Inflation Adjusted “because the increase in tornado reports over the last 54 years is almost entirely due to secular trends such as population increase, increased tornado awareness, and more robust and advanced reporting networks.” NOAA – Storm Prediction Center

You'll note the two prior low counts in the 10-year history were 2013 and 2012.
I have not seen a good explanation for this although it is probably just decadal variability.
No matter what the reason, the insurers are groovin'.