It all depends of the scale of the ISP and the number of end-users they have. That can range from a few hundred to multiple thousands and to the tens of thousands and beyond. It's directly proportionate to the number of users they have. The more users they have, the more likely it is that some users may be involved in infringing activities and that drives the volume of notices they might expect.
Evidence of meeting #126 for Industry, Science and Technology in the 42nd Parliament, 1st session. (The original version is on Parliament’s site, as are the minutes.) The winning word was film.
A video is available from Parliament.