Every quarter, Akamai publishes an interesting report called the "State of the Internet”, which examines internet penetration. The report for Q2 2014 shows that 98 % more people globally have fast enough internet to stream 4K compared to the same period last year.
South Korea is leading the way
Akamai is one of the largest CDN operators globally and they have a pretty good idea about the data flows on the internet. Akamai defines “4K Readiness” as an internet connection above 15 Mb/s.
Globally, 12% of all home broadband connections are “4K ready”, but there are major differences from region to region. South Korea is leading by a huge margin, as 62% can stream 4K video. Hong Kong is a distant second and Japan is third. All other countries in top-10 are European. USA ranks 15 with 19% readiness and the UK ranks 11 with 21%.
As the numbers indicate, more households are able to stream 4K video than most observers in the industry believe. With the adoption of HEVC it is possible to stream 4K at much lower bitrates than in the past. The internet could very well be the engine for 4K adoption, as few broadcasters have concrete plans to launch 4K channels. A 4K Blu-ray format is expected in late 2015.
Netflix is currently one of the few streaming providers to offer 4K. They use a bitrate of 15.6 Mb/s.
Akamai's methodology is interesting because they measure the flow of traffic on the internet; not just the theoretical peak speeds. If you want to read the full report it is available as a PDF here.