Over the last two years the concept of a 'Netflix' or 'Spotify' for books has grown from being an embryonic idea into a reality. Services like Scribd, Oyster and Kindle Unlimited all offer readers in the US, UK and beyond the chance to download and read ebooks on an all-you-can-eat basis in exchange for a monthly flat fee. Yet while these services are quick to point out the size of their catalogues and have been widely positioned as the future of content delivery in a world increasingly dominated by smartphones, they have been far slower to disclose how many paying subscribers they have.

Last week, we published some research into the reading and media consumption habits of 2,000 18-34 year olds (also known as 'millennials') on both sides of the Atlantic. We expected this research to throw up some interesting data showing to what extent this first 'digital native' generation were moving towards the subscription model.

As with the results we showcased on this blog last week we discovered that while subscription accounted for a significant slice of content sales and consumption, there were differences between the US and UK market that show they are both at very different stages. In the US, 22% of millennials said that they "normally" acquired new ebooks to read through subscription services such as Oyster or Kindle Unlimited, compared to 16% in the UK. Taken at face value, this would suggest that ebook subscription services have penetrated the market with remarkable speed, reaching a fifth of people in this key millennial group in just a few years. Yet it's also important to remember that our research concentrated on readers rather than the general population.

Nevertheless, the speed at which ebook subscription services seem to have caught on with habitual readers is impressive if we also compare their uptake with film, TV and music streaming services among the same age group. Here substantial differences appear between the US and the UK. Film and TV subscription services enjoy a very high market penetration among millennials of 45% in the US, according to our research. Netlfix is far less popular in the UK, however, as only 16% of the same group said they subscribed to film & TV services.

And despite having been active in the market for far longer than their film and TV or ebook equivalents, music streaming services like Spotify were not vastly popular on either side of the Atlantic. 18.5% of millennials said they subscribed to a music streaming service in the US, but only 11% did so in the UK. Instead it seems that millennials are still more likely to want to own the music they buy and listen to, rather than rent it by the month from a streaming service. 38% of US millennials said they still bought music in physical formats and 57% downloaded MP3s via services like iTunes. The trend was similar, if at generally lower levels in the UK, where 27% of millennials bought music in physical formats and 34% downloaded MP3s

Apps and games were the content category for which millennials on both sides of the Atlantic were likely to pay. 62% of 18-34 year olds in the US sales pay for downloaded apps and games, but only 40% of people in the same age group in the UK pay for this type of content. Yet perhaps the biggest difference between the UK and US emerged when we looked at the number of digital content refuseniks among our respondents. Only 11% of the US millennials we surveyed said they never paid for any type of digital content at all. In the UK that rose to nearly a quarter (24%) of respondents.

We didn't ask whether this was because these people just weren't interested in buying digital content or whether it was because they were pirating it instead, but one thing is clear. Subscription does indeed have its passionate advocates across several media forms, but with the exception of film and TV services in the US, it is still not a majority pursuit - even among so-called digital natives.