Kaylan actually cites Professor Lawrence Rothfield's recently edited book, Antiquities under Siege: Cultural Heritage Protection after the Iraq War (AltaMira, 2008), where it is estimated "that, every year, roughly 10% of Iraq's heritage was being destroyed".
Kaylan also quotes from Dr John Curtis of the British Museum, commenting on the observation there has been no further looting 8 out of some 10,000 sites in Iraq "it may not be typical of the country as a whole, and the situation could be worse further north."
Now Rothfield has responded to Kaylan:
I've already detailed, below, the evidence for looting, much of which comes from those political radicals the Polish civil-military brigade and the Italian carabinieri. (I shared all this information with the writer of the WSJ article, by the way, but he chose not to use any of it, for reasons that should be clear.)
(See also Rothfield's "Yet more looting in Southern Iraq".)