Dear Herman,
Perhaps the New Catalogus Catalogorum could be used at least to get an idea. But
for starters:
The Peking edition of the Tibetan Buddhist canon includes roughly 5500 Sanskrit
(including BHS, Apabhraṁśa and a few Pali) works in Tibetan translation. Many of
these are by no means "books" - in some cases, for instance, a single brief poem is a unique entry.
The Taishō Sino-Japanese Tripiṭaka includes about 1600 works of Indian origin. I do not know
if there is a readily available calculation of the degree of duplication with the Tibetan collections.
The current index to Karl Potter's bibliography of Indian Philosophy lists 8530 titles,
a few hundred of which are titles also belonging to the Tibetan and/or Chinese canons.
I imagine that the late David Pingree's Census of the Exact Sciences might similarly
afford some impression of the volume of literature in the astral and mathematical
sciences.
Perhaps this is at least a start.
Good luck!
Matthew
Matthew Kapstein
Directeur
d'études,
Ecole Pratique des Hautes Etudes
Numata Visiting Professor of Buddhist Studies,
The University of Chicago