According to the report, some 30,000 firearms were seized from criminals by Mexican officials in 2008. Out of these 30,000 firearms, information pertaining to 7,200 of them, (24 percent) was submitted to the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) for tracing. Of these 7,200 guns, only about 4,000 could be traced by the ATF, and of these 4,000, some 3,480 (87 percent) were shown to have come from the United States.
Now criminals are a greedy bunch and would you rather purchase $1,000.00 AR15s
In fact, due to this surge in demand, it is downright difficult to locate many types of assault rifles and certain calibers of ammunition, though a lucky buyer might be able to find a basic stripped-down AR-15 for $850 to $1,100, or a semiautomatic AK-47 for $650 to $850. Of course, such a gun purchased in the United States and smuggled into Mexico will be sold to the cartels at a hefty premium above the purchase price.
Or $100.00 fully automatic rifles?
By way of comparison, in places where weapons are abundant, such as Yemen, a surplus fully automatic assault rifle can be purchased for under $100 on the white arms market and for about the same price on the black arms market. This difference in price provides a powerful economic incentive to buy low elsewhere and sell high in Mexico, as does the inability to get certain classes of weapons such as RPGs and fragmentation grenades in the United States.
Now, I'm not an economist, but even I can see that I'd rather buy a $100 rifle than a $1,000 rifle. Criminals being the greedy people they tend to be, probably see this as well. Oh yeah, the last time I went into my FFL, I asked for that RPG and South Korean hand grenade. He said he'd work on it but don't hold my breath.
So from a certain point of view, 87% would be correct. The entire article can be found here.