How do I keep squirrels and raccoons from getting in my garage soffits and filling it with leaves etc until the soffit pieces fall out

How do I keep the squirrels and raccoons from filling my garage soffits with leaves etc until the soffit pieces fall out.
I had the soffits replaced two years ago because of this and they are back at it. I have to figure out how to put three soffit pieces up. Any suggestions would be helpful.