In Denver, the weed sales tax is upwards of 21% with a previous 15% excise tax from cultivator to retail outlet.
In Colorado, it's less than 8% tax on a 6 pack of beer and the great majority of this is a federal tax.
Weed is demonstrably safer and thus less sinful than alcohol and tobacco. I dislike how easily the tax argument is received. If you can show a relationship that adds to healthcare costs then by all means institute sin taxes, including for soda. But if you are only making a moral judgement about what not to do, then I think the argument is without merit.
More details-
http://reason.com/blog/2013/03/22/whatever-happened-to-treat...