A while a go, I released a simple website which reported on the number of items in UK repositories over time. It collected its data from ROAR but by collecting it on a weekly basis could provide a table showing growth week by week.
First it has a new home: http://www.nostuff.org/ircount/
Secondly, it now collects data for every institutional (and departmental) repository registered in ROAR across the world. Not just the UK. It has been collecting the data since July.
The country integration isn’t perfect, you have to select a country, and then you are more or less restricted to that country (though you can hack it, see the ‘info&help’), and there is a lot of potential with improving this. There are also a couple of bugs, for example when comparing four repositories it seems to (a) forget which country you were dealing with, and (b) it stops showing the graph/chart.
I’m currently looking at trying to make an educated guess at how many fulltext items are in a given repository. This is proving to be a steep learning curve in the joys of OAI-PMH, and how the different repository systems (and the different versions on these systems) have allocated information about the fulltext in to different Dublin Core (DC) elements. But this is for another post.
In the mean time, I hope the worldwide coverage is of some use, and feel free to leave any comments.