Total printed?

Does anyone know how to get reliable information on the total copies of a book printed, or sold?

Obviously it's not available for most books, but if I knew 20 books—of different types—then I could calculate the percent that made it to LibraryThing. (For some academic titles, I wonder if we're not sometime even 1% of the total, although I'd bet—on average—we were more like 0.01%.)

This doesn't answer your question, but here are two possible candidates for the outliers (although I'm not sure that I trust the LT data in the second case):

IKEA 2008 catalogue: 160 million copies printed, one copy on LT

Gutenberg Bible: 48 extant, 4 copies on LT

ETA: Possibly Nielsen Bookscan might be the real answer, at least for recent publications

Gutenberg Bible: 48 extant, 4 copies on LT

!!!

Color me stunned.

I would bet a small amount of money that those are facsimiles.

But I didn't add my IKEA catalog to LT! It's not so much a book, is it?

I'll bet there's some rough Rowling number out there...

Ah. Wikipedia says more than 400 million (http://en.wikipedia.org/wiki/Harry_Potter)

So, LibraryThing has 0.058% of the copies out there.

Assuming proportionality, LibraryThing can continue to grow for some time. If everyone added their books to LibraryThing, it would have 54,670,715,716 books.

I don't think you can assume proportionality. A few examples from the Wikipedia list (http://en.wikipedia.org/wiki/List_of_best-selling_books):

Da Vinci Code 57,000,000 24141 0.04235%
The Catcher in the Rye 65,000,000 20667 0.03180%
The Hobbit 100,000,000 24364 0.02436%
The wind in the willows 25,000,000 3638 0.01455%
Le petit prince 80,000,000 9975 0.01247%
The horse whisperer 15,000,000 1065 0.00710%
Heidi 50,000,000 2530 0.00506%
Merriam-Webster's Collegiate Dictionary 55,000,000 1898 0.00345%
Tale of Peter Rabbit 45,000,000 1537 0.00342%
Book of Mormon 105,000,000 1379 0.00131%
Boy Scout Handbook 40,000,000 400 0.00100%
She 83,000,000 650 0.00078%
Scouting for boys 150,000,000 45 0.00003%
Poems of Mao Tse-tung 400,000,000 27 0.00001%

...which rather suggests, even allowing for the unreliability of the data, that LibraryThing over-represents recent books and those with an interest for US readers. And that Maoism is more prevalent among LibraryThingers than self-assembly furniture. :-)

3>

Well, they certainly aren't genuine.

Some of them may be this work about the Gutenberg Bible, rather than facsimiles, as well.

Looking at a SF small press like PS Publishing (which is British) and choosing titles that have not been reprinted elsewhere (or which have electronic downloads, or which have the same title as a short story which might be available elsewhere) it seems that LT has about 1% of the copies catalogued.

Whether that means that LT has greater penetration amongst SF fans or that SF fans are more likely to want to catalogue books I don't know. But obviously I don't think it can be extended to major fiction publishers let alone non-fiction.

Its possible that some small presses may be disproportionally represented.

I went and looked at The Way of the Teacher. I know that about 600 copies have made their way out into the world and there are 7 catalogued on LibraryThing.