Why during a partial solar eclipse does the amount of light not decline in proportion to the amount of the sun covered up?

I was thinking about this a lot on Monday. I was in about 95% totality and it only got a little dark. I read that was the case before, but I don’t understand why. When I think about it light a lamp, I felt like the amount of darkness should be proportional to the amount of the sun that is covered, but it seems to basically be an all or nothing type of situation. Does the sun produce an abundance of light or something like that?