Around 40% of the world population has an internet connection today. In 1995, it was less than 1%. The number of internet users has increased tenfold from 1999 to 2013. The first billion was reached in 2005. The second billion in 2010. The third billion in 2014.
Internet Live Stats
Check http://www.internetlivestats.com/internet-users/ for more stats. Unsurprisingly, China has the most active internet users, but surprisingly Nigeria has the highest (relative) growth rate, followed by India and Russia.