more statistics that make you go "hmmm"

Constance Malpas had more statistics about California libraries, as well:

* CA represents 9% of US Academic Library holidings
*... and 8% of aggregate ARL unique titles
* 37K books borrowed from outside sources in 2006 in the UCs

About uniqueness among all institutions: (based on worldcat data)
* More than 50% of the titles that have been borrowed through ILL recently are held by less than 50 libraries

Based on 6 years of monographic borrowing at an ARL institution:
* 55% of the titles were requested only once: 45% of the titles were requested more than once; rarely held and rarely borrowed titles still represent a significant demand in the aggregate

Based on one consortia: In Ohiolink -- a consortium that has been very aggressive about preventing redundancy, there are still roughly 4.5 duplicate copies for each title
* but in the aggregate collection -- only about 50% of the titles in Ohiolink have ever circulated, at all
* Limited use of the collection as a whole, but use is very concentrated -- the 80:20 rule
* But it's worse than that: 6.5% of titles in circulation represent 80% of the total circulation

[Note: I didn't catch how she got the 4.5 copies number -- is that on average? Because it seems like obscure monographs might be held by one school while popular textbooks might be held by dozens ... but we didn't get into that level of detail].