90%

A much more detailed look:

In fact, the 3,480 guns positively traced to the United States equals less than 12 percent of the total arms seized in Mexico in 2008 and less than 48 percent of all those submitted by the Mexican government to the ATF for tracing.

Of course, we in the gun culture already knew that. The article goes into much more depth than just math and numbers. RTWT.

h/t Sebastian

pm