I don't have that statistic. However, I can comment that people with disabilities who live in urban communities most often do live independently. Some do live in group home environments and some live in apartment units, so they currently receive door-to-door service.
In rural municipalities or communities, most often people live independently within their own home, and as Holly mentioned previously, that same premise affects people with disabilities in smaller communities that have a post office where someone goes to pick up their mail.