How much do Internet users download every month? How is this likely to change as the Internet becomes more a part of daily life? How far below the curve are Australia and New Zealand, compared to the rest of the world – and why? Today’s post talks about traffic demands, bitcaps, and what it all means.

In most of the world, broadband plans are sold by download and upload speed, with no restrictions on the amount of traffic consumed. This has allowed for the Internet to become a viable delivery method for music and video, increasingly via legal means since the emergence of Netflix Streaming, Hulu, and YouTube. This isn’t the case everywhere, as I’ll explain below.

Good data exists on the growth of the Internet and IP traffic globally. Cisco research and publish traffic statistics and growth predictions, and I have integrated data from their “Cisco Visual Networking Index: Forecast & Methodology, 2009-2014” document into the chart below. Based on Cisco predictions, I have assumed a 34% annual increase in downloads for the average user.

Few providers report on how much traffic their subscribers are using each month. In many countries, the information just isn’t important enough to publish. In countries with bitcaps, it’s commercially sensitive information that might influence end users in their purchasing of broadband services. It might also raise questions about network dimensioning and peak demand amongst more technical consumers. Research companies and lobby groups such as “Market Clarity” and “The US Telecom Association” have however constructed models based on available data, and have freely published these results. I have taken US Telecom statistics for baseline data for Global, Western Europe, and US, and Market Clarity data for Australia.

Although the chart below shows only forward growth, I have tested US and Australian figures backwards (i.e. subtracting 25%) citing Comcast and Market Clarity (via Comms Daily) figures and found both the 34% p.a. growth assumption and the baseline utilization figures to be within reason.

With no good data from New Zealand, I’ve left it off the chart completely. Based on available broadband plans and pricing, it should be assumed New Zealand is somewhere under Australia. This low placement is presumably due to download limitations described below.

Australia and New Zealand are among the few countries in the world where telecommunications providers limit the amount of data that can be downloaded in a month on broadband services. This limit is variously called a “Data Limit”, “Download Limit”, “Monthly Download Allowance”, or “Traffic Cap” – depending on the particular provider. The OECD in their “Communications Outlook” list all countries with these limitations, and refer to the practice as a “Bitcap”, a term we will use below.

The practice of bitcaps in New Zealand came about as a method of limiting network congestion on overseas circuits. They are effective as a way for providers to encourage users to limit their use, and to recover financially from those users who do not limit their use. They are particularly useful to mobile broadband providers, who heavily oversubscribe capacity on their last mile wireless networks.

As of February 2011, limits in New Zealand range from as low as 1 gigabyte of data a month on starter plans, to 100+ gigabytes per month on premium plans. A one gigabyte bit cap could be exhausted in twenty minutes of heavy downloading on an ADSL2+ circuit, but might take up to 10 hours to exhaust on a mobile broadband connection. As for what you can fit in to one gigabyte, the “Broadband Genie” has a number of examples of file sizes for emails, web pages, photos, songs, and videos.

While bitcaps remain in place, Australia and New Zealand are unlikely to catch up with the rest of the world. New telecommunications infrastructure in Australia via the NBN and in New Zealand via the UFB and the potential for a new undersea cable to the US could result in the elimination of bitcaps, but this is speculation.

On a final note, the astute reader will notice no mention of South Korea. While South Korea is included in the global averages, their inclusion on this chart would break the scale. Its users averaged 24.5 gigabytes per month in 2009.