As has been noted in this blog, the Census does not, indeed cannot, ask mandatory questions about religious affiliation. This doesn't mean other people can't take a crack at it. The Graduate Center, the doctorate-granting institution of The City University of New York, has a series of reports such as the American Religious Identification Survey, American Jewish Identity Survey and the Latino Data Project. Of course, some statistics have great sociological implications. The author of this article, for instance, believes that the number of Jewish people in America has been underestimated. Still, both of these are self-identified numbers, rather than the denomination-driven stats provided, e.g., in the The Yearbook of American and Canadian Churches. Make of these what you will.
Incidentally, the Graduate Center has other reports at the link above, such as Philanthropy Among African American, Asian American, and Latino Donors in the New York Metropolitan Region; First Comprehensive National Study Finds Centers Safest Form of Childcare; and Echoes of Brown: The Faultlines of Racial Justice and Public Education.