Well, whether it is a surprise depends on how you look at, I guess. On the one hand, as population grows and infrastructure expands to support that population, it's true that there are more assets exposed to damage from natural disasters. By that token, it isn't surprising that the cost of disasters has risen since NOAA started tracking it consistently in the 80s. But at the same time,  it does surprise me a bit that with all our "progress"--the ability to better forecast certain disasters, better understanding of material science and construction techniques, the possibility of drone monitoring, etc--the US hasn't been able to translate that knowledge into a reduction in the costs associated with natural disasters.