It's not hard for a tornado to rip a house off its foundations, especially if it knocks down a tree and uses that or something else as a broom.

You can't learn anything useful about weather over such a short period as three years - you need to look over longer periods. The National Weather Service has long used 30 years as their interval for giving "normal" conditions.

It's probably too early in the season to gather meaningful statistics to compare against prior years.