Aren't the majority of English speakers from the US?
EDIT: The USA has 3x the population of the UK and Australia combined and the USA appears to be the home of approx 60% of native English speakers. However there are billions of speakers if you include it as a 2nd language. Which Americans don't speak 2nd languages so we obviously don't count that.
I'd just like to mention that plenty of ESL users speak English more than their native, and that the country with the most people who use English for interacting with the Internet, it's probably India. Indians communicate to a lot of their compatriots in English, since they are also an ex-British colony, and have a large variety of native languages.