The number I have seen approaches 100 million. It will take me a little digging to find the source. The problem with the statistic is that "single" does include people who were once married, but no longer so. A case could be made that a meaningful measure should also include those who intend to get married. I suppose the real statistic should be those who do not want to get married plus those who have no hope of getting married. I admit that I have not seen that statistic.
