The Association of Research Libraries has released ARL Academic Health Sciences Library Statistics 2007-2008 (print version also available).
Here's an excerpt from the press release:
The Association of Research Libraries (ARL) has published the ARL Academic Health Sciences Library Statistics 2007-2008, which presents data that describe collections, expenditures, personnel, and services in 64 medical libraries at ARL member institutions throughout North America.
In 2007-2008, the reporting health sciences libraries held a median of 240,955 volumes, spent a total of $240,019,298 and employed 2,304 FTE staff. Expenditures for materials and staff accounted for the bulk of total expenditures, at 49% and 42% respectively. Respondents reported spending a total of $81,986,136 for electronic materials, or an average of 76% of their total materials budgets; this includes a total of $76,921,558 for electronic serials.
See also ARL Health Sciences Statistics Tables 2007-08 (XLS file).