Usage Statistics

Use by specified UK academic institutions

You can request a graph and table showing an annual summary of Copac use for any address. Enter the address into the box below, choose the required year, then select the 'Get stats' button. You can then download the usage figures as a .csv file for loading into a spreadsheet.
Note: Web usage stats before and after Aug 2009 are not directly comparable.


A couple of things to be aware of:

  • Use by members of an institution will be an underestimate as it excludes those many academic users who access Copac from home.
  • In a few cases users from a single institution access Copac with two different addresses and you need to search for these separately, eg. and

General use summary - 1996 onward

The graph below illustrates usage of Copac from 1996 onward. It includes total usage as well as a breakdown by interface ie. Web (including OpenURL access) and Z39.50. Short term usage via the early telnet interface, as well as small scale experimental access, has been excluded from the graph for clarity, but is included in the total usage line. The figures before and after the interface revision in August 2009 are not directly comparable

The usage figures are given in terms of sessions, each session may contain multiple searches. Before we moved hardware some years ago we started to experience response time problems during peak periods, so the graph also includes the number of sessions being blocked from the Karlsruhe Virtual Catalog for a short period to mitigate response time problems arising from high usage levels.

Graph summarising Copac use since 1996

Notes on the figures:

Occasional hardware problems can show up as sudden drops in usage levels.

October 2009

A problem with the database software resulted in two separate occasions when the service was unavailable, lasting c. 3 hours each time. This will have resulted in a reduction in usage.

Interface revision August 2009

The release of a revised Copac interface in early August 2009 involved major changes to the way Copac worked behind the scenes. One side-effect of this upgrade was a change in the way we count search sessions.

In the past each time someone accessed Copac from the home page this started a new session, so a searcher could have several sessions in a single day. By contrast, an individual's search sessions are now potentially endless, so we are splitting them up by day. This means someone using Copac will now be counted as having one session on a specific day, no matter how many times they access Copac that day.

Consequently, figures before and after the 2009 interface revision are not directly comparable.