An email says,
In the latest issue of Harper's, in its Harper's Index, you can find these interesting statistics:
Confirmed number of terrorist plots against the U.S. perpetrated by Muslims in 2010: 10
By nonMuslims: 25
So: out of a total of 35 confirmed plots, Muslims were responsible for about 33% of them.
More:
An ad in this issue by Negative Population Growth states the present US population as 308.7 million people.
Generally the estimate (generous) of American Muslims is estimated at about 5 million.
Thus, Muslims constitute 1.6% of the American population but are responsible for 33% of the terrorist plots.