You know I have been in the aviation business for roughly 25 years
both military and civil. I have seen tail draggers from Citabrias up to DC-3s
even B-17s takeoff and land and have never witnessed a groundloop.
I'm sure they happen, but they don't seem to be all that common. The
field I work at, Morristown Municipal, has a huge variety of traffic and pilot
skill levels including students.