A Ten-Year Tornado Climatology for the U.S.
Because the states vary so much in size, it is better to examine tornado density (number of tornadoes per 10,000 sq. miles).Unless this is done, looking at the tornado total for Kansas and then Texas wold give misleading results since Texas is much larger than Kansas.
This map, produced by the Storm Prediction Center of NOAA highlights the ten year period 2001-2010 and measures the frequency of tornadoes per unit size or area of 10,000 square miles.
The highest density is in Kansas followed by Florida. Illinois and Iowa have a higher density than Nebraska.
Nebraska has had a total of 524 tornadoes for this time period (see: http://snr.unl.edu/extremeweather/netornado/Nebraska-Tornado-Totals.asp)
or an average of 52 tornadoes per year during that time period and it's size is 77,358 sq. miles giving it an average of 7 (actual number 6.77) tornadoes per 10,000 sq miles.