Is the frequency of strong tornadoes up, down, or stable during recent years? Down is the answer.
In the 58 years from 1954 to 2012, there have been 20 years that have had 50 or more F3 or stronger tornados. But from 2000 to 2012, there were just 2 years with 50 or more F3 tornados.
As a result, from 1954 to 2000, 50 or more F3 tornados in a single year hit every 2.5 years. Yet, since 2000, the frequency of a year with more than 50 F3 tornados has fallen to once every 6 years.
The worst year for strong tornados was 1970 with 130, followed by 1965, and 1957--the year of my birth.