The Pew Research Center has released Social Media Use Continues to Rise in Developing Countries but Plateaus Across Developed Ones.
Here's an excerpt:
Across the 39 countries, a median of 75% say they either use the internet occasionally or own a smartphone, our definition of internet use. In many advanced economies, nine-in-ten or more use the internet, led by South Korea (96%). . . .
Across 39 countries, a median of 53% say they use online social networking sites like Facebook or Twitter. However, that figure conceals large differences around the world, and the relationship between social media use and national wealth is not as strong as it is for overall internet use and smartphone ownership.