How Many of Us Are There Anyway?

I've never liked surveys like the National Jewish Population Survey. American Jews are, in their Holocaust-influenced way, obsessed with counting themselves over and over again. The results are never encouraging. The number of Jews keeps dropping despite the efforts of the Reformers to count everyone and their devoutly Catholic mothers-in-law as members of "the tribe". New York City alone used to have more Jews than Israel. Now the entire U.S. population is smaller than the State's.
As a result, the definition of Jewish continues to morph, in a desperate attempt to prove that we are, as an assimilated and barely educated population, not shrinking into a demographic disaster.
Time was, the definition of being Jewish was simple: either your mother was when she popped you out, or you converted al pi halachah. New surveys, however, expand this. Any conversion, no matter how hokey, seems to get you included, as does patrilineal descent. Years ago I saw one survey that included a group of people with no legal connection to the Jewish nation but who feel they were "Jewish in spirit". They also added to the count.
I have a simple question: how many Jews are left in America al pi halacha? Officially there are 5.2 million of us but I wonder: what shrinking fraction of that is actually legitimate? And how do we find out?