The problem with using government statistics (including the American Community Survey, as far as I can tell) is that "single" is roughly equivalent to "anyone who is not married", which is very different from "willing to date".

That means that people who are in a committed relationship but haven't gotten married yet, or perhaps never want to get married, are considered single. There are also people who are simply not interested in dating or relationships. Consequently, the dating pool is even smaller than the statistics would suggest (assuming we're not counting currently-married people who are in the dating pool due to separation, infidelity, or being in a poly/open relationship).