We had a great discussion at my table recently about the frequency of different saving throws, which got me thinking...

Inspired by my previous similar question, what are the most and least common saving throws?

To narrow the scope a bit, I'd be looking to evaluate the most and least common saving throws based on player spells in all officially published materials, though bonus points to answers which also consider other sources of saving throws (e.g. unique monster abilities, magical items, class features, etc).