> I think you picked the cutoff (70) so that the numbers look worse than they are.

Reminds me of a point I heard about sports statistics. If a given team is reported as having "won 4 out of their last 7 matches", there are good odds that they also won 4 out of their last 8 matches. Also pretty good odds that their seventh-last match was a win, otherwise the stat would be 4 out of 6. (It could also go the reverse direction if the goal is to make it look worse than it is.)