Dr. Harold Brooks looks at how the U.S. tornado count in 2012 compares historically:
One way of thinking about the late spring and early summer tornado season is that the atmosphere missed more than 40% of a typical year’s tornadoes in 3 1/2 months. Compared to 2003, the comparable period in 2012 had more than 900 fewer tornadoes.
Brooks also discusses issues that arise in attempting to make such comparisons. Worth the read.