With IPv4 addresses running out, the Internet needs to make a big switch to IPv6 to keep things rolling. So far the adoption is going pretty slow, it was under 6 percent a year ago and on December 26, 2015 it was still only 9.98 percent. Full details at ARS Technica, they explain the significance and why it's taking so long to upgrade to IPv6.
Google also keeps a map of the world with IPv6 deployment numbers per country, handily color-coded for our convenience. More and more countries are turning green, with the US at nearly 25 percent IPv6, and Belgium still leading the world at almost 43 percent. Many other countries in Europe and Latin America and even Canada have turned green in the past year or two, but a lot of others are still stubbornly staying white, with IPv6 deployment figures well below one percent. Some, including China and many African nations, are even turning red or orange, indicating that IPv6 users in those countries experience significantly worse performance than IPv4 users.