DOCS: Books ever published in US; total OP titles

A team of MBA students is trying to find out (for a business client who wants to start a re-publishing venture):

a) number of books ever published in the US
b) number of these now out of print
c) number of books ever copyrighted in the US
d) number of these now out of print

for different ranges of years, including:

a) pre-1923
b) all years since 1900
c) since 1985

We've used these sources, but all have problems:

a) BIP database (incomplete reporting, especially for older titles)
b) Bowker Annual (don't have all years, no OP information)
c) Publishers Trade List Annual (now ceased in UO)
d) Catalog of Copyright Entries (includes many titles not handled by book trade)
e) Copyright registrations database, 197?-date (query-only, cannot use for metrics)
f) Copyright Office anual report (includes many non-book trade titles)

Can anybody suggest a methodology that we haven't thought of?

Tom