I just learned of this report (*Commissioned for and sponsored by the
National Film Preservation Board, Library of Congress*) and felt the need
to share it here.  The PDF is linked here:
At first it may seem silly to bring up silent films on a recorded sound
listserve, but the way author David Pierce hunted down original materials
and reports on the current state of preservation is fascinating.

The author breaks down survival info by year, by studio, by format, by
location today (U.S. archives, foreign archives, libraries, pvt.
collectors).  He charts survival rates for complete films vs. one reel
missing vs. other breakdowns.

There are terrific embedded images and fascinating case studies,
particularly the one on Paramount Pictures - the most successful silent-era
studio, and sadly one with a very poor survival rate.  I haven't had time
to read the whole thing, so I can't speak for what else he presents.

I believe the author's methodology would also work well for studying the
survival of early sound recordings, and I hope someone in such a position
finds inspiration here.