Figuring out how much caffeine things contain

It just occurred to me that, while there's now a lot of information provided on packaging about what is contained in the things we eat and drink, the amount of caffeine is missing from that info. If, like me, you want to be careful about how much caffeine you take in (without necessarily wanting to dispense with it completely!), then it would be invaluable to have some indication on the packaging.

Take, for example, all the "one cup" drink sachets - cappuccino, latte, mocha, etc - how much caffeine does each of these contain? I can estimate the amount of caffeine in a teaspoon of instant coffee, or in a cup of filter brewed coffee, but I have no idea how much actual coffee or caffeine is contained in any of these "just add water" drinks. Or consider drinking chocolate, or cocoa, or a bar of chocolate (I know that doesn't contain caffeine as such, but it does contain a chemical very similar to caffeine, which has a similar effect on the body).

Caffeine is as much a drug (and addictive at that!) as nicotine, and whenever it's present in a drink or food item, the amount should be shown.