Peter Bryenton asked "I was wondering how much caffeine there is on average in an ordinary cup of instant coffee?"
Not an easy question as the consumer is in control of how strong they make the coffee and how big a cup they use. Generally instant coffee powder is about 2-3% caffeine and instant coffee is about 330mg/L (about 75mg per cup). But I know my first cup of coffee in the morning is considerably stronger than my last of the day.
Tea is generally only about 80% of the caffeine levels of coffee but, again, this varies with type, cup size and steeping time. Herbal teas generally have none but be careful of flavoured green teas, they have similar levels to black tea.
Colas are about 100mg/L; a third that of tea and coffee.
The much vaunted 'Energy Drinks' are only permitted a maximum of 320 mg/L in Australia and so are on a par with tea and coffee. Not that they would want an image of a little old lady sipping her cuppa to be equated to the macho image of the heroic energy drink urban warrior-rapper-sportsman.