The Primary Research Group has published The International Survey of Institutional Digital Repositories. Paper and PDF versions are available at $89.50 each.
Here's an excerpt from the press release:
The study presents data from 56 institutional digital repositories from eleven countries, including the USA, Canada, Australia, Germany, South Africa, India, Turkey and other countries. The 121-page study presents more than 300 tables of data and commentary and is based on data from higher education libraries and other institutions involved in institutional digital repository development. . . .
Close to 41% of survey participants purchased software to develop their digital repositories. US-based institutions were much more likely than others to purchase software for this purpose. . . .
On average, a drop more than 12% of the content in the repositories came from pre-existing repositories maintained by academic departments or some other institutional unit.
A sixth of the libraries in the sample used Digital Commons software, and 28% of US-based repositories used this product. . . .
Those repositories in the sample that required less than 500 hours of labor per year had budgets of just less than $9,000 US. The largest repositories, those requiring 3,600 hours or more annually, had budgets averaging $145,444. 5.21% of the overall labor required to run the digital repositories in the sample came from academic departments not connected to the library. . . .
The mean number of journal articles held by the repositories in the sample was 772 with a mean of 162. . . .
15.56% of the repositories in the sample were funded largely through grants.