Orin Kerr points out an article by Lori Ringhand counting the number of times that members of the Rehnquist court voted to strike down legislation over a given period. With the exception of Chief Justice Rehnquist (who was markedly less inclined to strike down legislation), Kerr reports that all of the Justices voted to strike down legislation between 57 and 67 times.
What is interesting is that the "conservatives" were far more likely to strike down federal laws while the "liberals" were more likely to strike down state laws. This is what you'd expect but it tends to illustrate that the debate around "judicial activism" is not really about striking down legislation. That certainly is part of it but how many times and under what circumstances legislation is struck down is going to depend on what legislatures do. Professor Ringhand's numbers, while not, I suppose, unexpected or an entirely new revelation, prompt us to think more about the underlying philosophies in the activism/restraint debate.