It varies widely, but since the U.S. averages 1200 tornadoes in 1 year, it would average 2400 in 2 years. Worldwide figures are not available as many countries do not keep records of their tornadoes.
There were 949 recorded tornadoes in Illinois in the years 2000 to 2016.
In the years 2001-2002 Georgia had 36 confirmed tornadoes.
On average Birmingham gets hit by a tornado every two years.
Based on records from the past two decades, Vermont averages about one tornado every two years.
In the U.S. there were 14,626 confirmed tornadoes in the years 2001-2011.
Only one. Like many things, no two tornadoes are exactly alike.
In the years 2000-2010 there have been 13,817 tornadoes confirmed in the United States.
There have been about 6,300 tornadoes in the U.S. in the past 5 years with more worldwide.
As of April 28, 2015 Georgia has had 125 tornadoes in the past 5 years.
There were two tornadoes in the state of Washington in 2011.
There were two weak tornadoes in the sate of Washington in 2010.
In the past 25 years Bloomington-Normal has had 2 tornadoes