English-speaking population is about 1.5 billion worldwide and 300 million of that is in the US (first language or additional language), so the US is about 20% of the world’s English speakers. The 2nd and 3rd countries with the most English-speakers are India and Nigeria, so factor in internet access, and the US is almost certainly >20% of the English-speaking internet.
Source: https://en.wikipedia.org/wiki/List_of_countries_by_English-speaking_population
For the lazy, three of his kids died before 30:
Worth noting the life expectancy when Mark Twain was born was about 60-65, so he did outlive the average by 10-15 years. But this is still more due to his children having tragic deaths rather than his longevity.