Precise figures on request, of course.
Also, aluminum is not zinc. Comparisons between the two are in fact rather stupid.
BTW, if you want to be an aluminum ''thief'' as it were, you are far better off targeting foil manufacturers than breweries.
As far as that goes, you're far better off salvaging gold from old computers (the circuit boards, dontchaknow). All it takes is a file and a bit of patience -- how easy, and no theft involved.
www.coinflation.com
Canadian coins do even better
1955 - 1981 Nickel
metal value $0.2224582 (US)