What is the distribution of Saving Throws associated with each attribute that are required by spells?

I read somewhere that in D&D 5e, the Saving Throw distribution for spells was biased towards DEX, CON and WIS. In other words, if you had proficiency in those attributes, you would benefit a lot more than having proficiency in other attributes.

What is the distribution of Saving Throws across attributes for spells in D&D 5e?

I’m looking for a percentage of each attribute for all the spells available (one would expect this to be uniform). Bonus points if this is also calculated for only spells that can be cast by RAW monsters (MM and VMG).