Thanks to edmundedgar on reddit I have some more accurate data to update my previous bandwidth growth estimation post: OFCOM UK, who released their November 2014 report on average broadband speeds. Whereas Akamai numbers could be lowered by the increase in mobile connections, this directly measures actual broadband speeds.
Extracting the figures gives:
- Average download speed in November 2008 was 3.6Mbit
- Average download speed in November 2014 was 22.8Mbit
- Average upload speed in November 2014 was 2.9Mbit
- Average upload speed in November 2008 to April 2009 was 0.43Mbit/s
So in 6 years, downloads went up by 6.333 times, and uploads went up by 6.75 times. That's an annual increase of 36% for downloads and 37% for uploads; that's good, as it implies we can use download speed factor increases as a proxy for upload speed increases (as upload speed is just as important for a peer-to-peer network).
This compares with my previous post's Akamai's UK numbers of 3.526Mbit in Q4 2008 and 10.874Mbit in Q4 2014: only a factor of 3.08 (26% per annum). Given how close Akamai's numbers were to OFCOM's in November 2008 (a year after the iPhone UK release, but probably too early for mobile to have significant effect), it's reasonable to assume that mobile plays a large part of this difference.
If we assume Akamai's numbers reflected real broadband rates prior to November 2008, we can also use it to extend the OFCOM data back a year: this is important since there was almost no bandwidth growth according to Akamai from Q4 2007 to Q7 2008: ignoring that period gives a rosier picture than my last post, and smells of cherrypicking data.
So, let's say the UK went from 3.265Mbit in Q4 2007 (Akamai numbers) to 22.8Mbit in Q4 2014 (OFCOM numbers). That's a factor of 6.98, or 32% increase per annum for the UK. If we assume that the US Akamai data is under-representing Q4 2014 speeds by the same factor (6.333 / 3.08 = 2.056) as the UK data, that implies the US went from 3.644Mbit in Q4 2007 to 11.061 * 2.056 = 22.74Mbit in Q4 2014, giving a factor of 6.24, or 30% increase per annum for the US.
As stated previously, China is now where the US and UK were 7 years ago, suggesting they're a reasonable model for future growth for that region. Thus I revise my bandwidth estimates; instead of 17% per annum this suggests 30% per annum as a reasonable growth rate.