Everything you need to know about the export and import of ammunition from and to the United States is available on workshop.chromeexperiments.com/projects/armsglobe/. This data goes back as far as 1992. The same, or even better information, can be obtained from any of the large gun and ammunitions suppliers like Winchester and Colt.
I read a study awhile back, can't recall the name of it ATM. Lets just say their is approx. 140 bullets for every man, women and child on earth. And they are still making them faster then people are born. That a lot of lead!