This is the percentage of American internet users as per research conducted by Pew Research, one of the world's most reputed research organizations.
You can view the latest research (for 2016) here - http://www.pewinternet.org/2016/11/11/social-media-update-2016/
The report has also been republished in a more visual form by SproutSocial here - http://sproutsocial.com/insights/new-social-media-demographics/
These numbers are only indicative as no such detailed credible research is available for India at the moment.
Hope this clarifies!