Are Iraniam IED's Killing our troops?

ThinkProgress has an excellent piece here on Michael Gordon's latest hack piece on the Iraq war in which he regurgitates the adinistration propoganda about Iran killing our troops in Iraq. His claim is that our troops are being killed by Iranian made IED's. As Evidence he writes

General Odierno said Iran was increasing its support to Shiite militants in Iraq to step up the military pressure on the United States at a time when the Congress is debating whether to withdraw American troops.

“I think it is because the Iranians are surging support to the special groups,” he said, referring to the American name for Iranian-backed cells here. “Over the last three to four months, it has picked up in terms of equipment, training and dollars.”

If this were so you would expect to be seeing an increase in IED casualties this year compared to last. However, we see exactly the opposite, while we continue to see an increase in overall casualties this year by about 25%. Here are the IED casuulties trend lines.

As you can see the proportion of casualties attributable to IEDs is falling rapidly since May.

If the Iranian's have been providing a large supply of these devices it looks like they have been doing us a favor by supplying duds. Perhaps we should thank them for the declining rates.