Following this article (French), official phone eavesdroppings again increased in Belgium in 2009: Belgian police listened 5265 times to private conversations. The French transcript is here.
One doesn’t get much more than these numbers: nothing about the number of hours spent listening, nothing about the percentage of effectiveness/results, nothing about internet eavesdropping (e-mail e.g.). One thing struck me: all requests for eavesdropping were accepted. Or, at least that what the Minister implied when he wrote “there is no distinction between the number of requests and the number of effective eavesdropping”.