The Commission has issued a report on its relations with the national parliaments and the activities of these parliaments vis-à-vis the Commission.
Instead of starting to read the full text, I recommend starting with the Annex on pages 12-14, because there you have a nice overview over how active member states' parliaments were in 2009.
Very interesting to note is that Portugal was by far the most active country sending opinions to the European Commission (the Barroso bonus?).
And it is also worth noting that in countries where there is a second or higher chamber, this chamber seems more likely to issue opinions than the main parliament (maybe because the main parliament's majority has usually control via the government).
However, it will be very important to compare these figures with the figures for 2010, because this will be an indication whether the Lisbon Treaty rights for the national parliaments actually made them more involved with EU legislation.