There are some state documents at the New York Public Library's Humanities and Social Sciences Library - the big one with the lions, on 5^th Ave. - that might have the numbers you're looking for, and would likely be worth looking at for your research in general.

The Annual Report of the Inspectors of State Prisons, for which the catalog record lists holdings from 1848-1877 ("Library has: no.1-6, 8-14, 16-28 (1848-53, 55-61, 63-75)"), may have the statistical data you're looking for. That title is continued by the Annual Report of the Superintendant of State Prisons, for which the "Library has: 1876/7-1925/26(Incomplete)".

I suspect these might be found in large bound volumes of state legislative documents - that is the case in our New Jersey Collection - but the librarians in Humanities-General Research-Rm315 should be able help you out.