The graph above shows data on normalized US hurricane losses 1900 to 2009
and was presented in a talk I gave today. Why is there no trend in the data? The two graphs below explain why. You can do the math.
There are no trends in normalized damage since 1900 because there are no trends in either hurricane landfall frequency (data from NOAA) or intensity (data from Chris Landsea through 2006) over that same period (but rather, a very slight decline in both cases). If our normalization were to show a trend then it would actually have some sort of bias in it. It does not, thus we can have confidence that the societal factors are well accounted for in the normalization methodology.