Behind the Learning Curve

What bothers me most about this NYT graph of I.E.D.s in Iraq is that as the number of I.E.D devices deployed increases the number of I.E.D. devices safely found stays relatively constant. This not only indicates that the insurgency's production capacity is steadily increasing, but additionally implies that either the insurgency is learning and adapting deployment tactics faster than coalition forces can effectively respond or there is some saturated maximum capacity at which the coalition can find and destroy I.E.D.s. Either dynamic has disastrous consequences for trying to gain control in Iraq.