Tornado climatology
The United States averaged 1,274 tornadoes per year in the last decade. April 2011 saw the most tornadoes ever recorded for any month in the US National Weather Service's history, 875; the previous record was 542 in one month. It has more tornadoes yearly than any other country and reports more violent (F4 and F5) tornadoes than anywhere else.
List of F5 and EF5 tornadoes
In all, 63 tornadoes have been officially rated F5/EF5 since 1950: 59 in the United States and one each in Italy, France, Russia, and Canada. The works of Grazulis also revealed 16 more F5 tornadoes between 1950 and 1995, with four later being accepted by the NCDC. Since the implementation of the Enhanced Fujita scale on February 1, 2007, there have been nine officially rated EF5 tornadoes in the United States from May 4th, 2007-May 20th, 2013 to date, while previously fifty tornadoes were officially rated F5 on the original Fujita scale from May 11th, 1953-May 3rd, 1999.