1950-2011 Oklahoma had 1362 recorded F0 or EF0 tornadoes. For 2012 so far there is a preliminary count of 4 EF0 tornadoes in 2012. Though this will likely go up as a number of recent tornadoes will likely be rated, and still more will come in from reports that were not initially published.
It is important to note, however that prior to the 1990s a significant portion of tornadoes that would be rated F0 were missed, with the vast majority being missed through the 1970s. Because of this, the number of tornadoes of F0 strength that have occurred in Oklahoma is probably much higher.
The National Weather Service records 63 tornadoes in Oklahoma in 2012. See the link attached below.
Since official record keeping began in 1950 through 2012 there have been 971 tornadoes recorded in Ohio.
There were four tornadoes in Oklahoma in March of 2012, none of which resulted in any deaths.
Since official record began in 1950 up through the end of 2012, there have been 3,139 recorded tornadoes in Florida. Tha actual number of tornadoes is probably much higher, as prior to the 1990s, many of the weaker tornadoes were missed.
It is impossible to say for certain, as official records only extend back to 1950, and up until the early 1990s many of the weaker tornadoes that no doubt ocurred were never recorded. That said, from 1950 until 2012 there have been 8,117 tornadoes recorded in Texas.
From when official records began in 1950 up through 2012 there were 233 tornadoes recorded in Arizona. The actual number of tornadoes is likely significantly higher, as the vast majority of tornadoes in Arizona are weak. Such tornadoes were frequently missed in the earlier part of this time period. Even today a fair number of tornadoes that occur in sparsely populated areas likely go undocumented.
Since records began in 1950 through 2011 (data so for 2012 is not finalized) there have been 1181 recorded tornadoes in North Carolina. The actual number is probably significantly higher as the majority of weak tornadoes were missed in the earlier part of this period.
From 1950-2012, for which official records are available, Texas experienced 8,117 recorded tornadoes. The overall number is likely higher, as prior to the 1990s many of the minor tornadoes were missed.
Since records began in 1950, through 2011 there were 3651 tornadoes in March (for an average of 59 per year). The number in March 2012 is highly uncertain. There were 3 confirmed tornadoes on March 1. As of March 2 there is an extremely large tornado outbreak ongoing. The number of tornadoes will be in the dozens, but it is impossible to know what the final number will be. Surveying and confirming these tornadoes will take days.
There were 31 recorded tornadoes in Illinois in 2012.
There were 95 recorded tornadoes in Kansas in 2012.
Generally tornado season in Minnesota is considered to be peak from mid-May until the middle of August. While tornadoes have occurred as early as in March and as late as October, the periods of May, June, July and August are customarily considered Minnesota's tornado season.