Just how much caffeine is in caffeinated foodstuffs?

io9.com — 90% of North Americans consume caffeine on a daily basis. When ingested by itself, caffeine is extremely bitter — not the type a flavor many of us want lingering on our taste buds. Some foods naturally offer substantial amounts of caffeine, while other companies load up caffeine into... Feb 3, 2012 View in Crawl 4

Just how much caffeine is in caffeinated foodstuffs?