I would venture a guess of about 5%. From their perspective, some people are not PC literate and if they got along without using one all these years, what is their incentive to change?
Having worked in the PC industry, you can give the user all the user manuals that are need to resolve easy problems. The minute something doesn't work to perfection, they pick-up the phone to call the helpdesk. The manuals gather dust. Some people rely on other people who know just a tad more, as it's easier to call that person.
It's just the way it is for some people.
It is a shame as the internet really is an interesting tool for finding solutions to one's problems as well as exploring the web for videos, etc. It can open a whole new world for those who want to know more and do more.
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"It doesn't cost "nuttin", to be nice". 
MOM
I just want to do the right thing! Uncle Joe, (my hero).