I'm not sure what the ratio is. What I do know is that there is a concept that, to me used to be a well known concept, that web developer's are encouraged to follow called "graceful degradation". I wish more people would pay it some attention.

Whether it's due to capabilities of a browser or extra security measures a user would like to practice graceful degradation allows content to be shared with more people than not.

https://www.w3.org/wiki/Graceful_degradation_versus_progress...