I would say that for the components of voting in secret, 100% of people who are totally blind are excluded, because there is absolutely no way to be able to verify your vote. You have to have somebody else there to verify the vote.
As everybody else does, I can take it in, I can use the Braille template, and I can check my mark on the piece of paper, but it's important that we all check to make sure that we didn't accidentally spoil the ballot. I would say it is 100% of the people who are totally blind.
People who can read large print, and people who have some ability to read with magnifiers, would have the ability to do this on their own, but I couldn't tell you exactly what that portion is.