Boring to some, to others repetition is a process which eventually builds understanding and memory.

Having gone through the process of researching and writing the PocketGamer.biz Top 50 Developers list over the past five years, I can agree with both feelings.

More positively, however, the process does provide us with five years of data we can analyse in a different manner to the annual refresh.

So in this Chart of 'Week', I've been looking at those companies who have appeared in multiple list, and seeing what they can tell us about industry trends.

5 out of 5

Six companies have appeared in every Top 50: EA Mobile, Gamevil, Gameloft, DeNA, Glu Mobile and Backflip.

Perhaps this shouldn't be a surprise. With the exception of Backflip (which was majority bought by Hasbro in 2013), these are well established and well run, large or very large publishers, which are floated on stock exchanges and hence have the ability to raise the cash required to make big investments.

Of course, this status doesn't mean that they have all thrived over the past five years. Glu Mobile didn't deliver a profitable year during the period, while DeNA is currently suffering due to the structural turmoil in the Japanese mobile games market.

Yet, thanks to their ability to consistently deliver high quality games and broadly deal with changes in the mobile ecosystem - from a paid US-centric iOS market in 2010 to a free-to-play global iOS and Android market in 2014 - all six have remained in the top half of our Top 50 list.

4 out of 5

When it comes to the eight companies who have featured over the past four years, the situation is a different.

These are a real mixture from F2P social mobile start-ups such as Pocket Gems and Storm8, to more traditional paid mobile developers like Halfbrick, Chair and ZeptoLab. NimbleBit continues (just) to fly the flag for indies, while Miniclip has made the most of the mobile opportunity provided by its reservoir of popular Flash games.

But what's interesting to see is that unlike the '5 out of 5 companies' the position of the '4 out of 5s' is much more dynamic and downward. This demonstrates increasing market competition, as well as the declining power of the paid model used by ZeptoLab, Chair and Halfbrick.

Of course, the best example of this is the trajectory of Rovio, which hit the #1 spot in 2012 only to see its position fall away as it failed to hook into the free-to-play business model; something it is now looking to quickly remedy.

Hello stranger

And that's because the most significant trend on our Top 50 list remains the number of new entries each year.

Certainly, it's decreasing with 13 new entries in 2014, compared to 19 in 2013 and 23 in 2012. Still, 13 new entries is over 25 percent churn.

If nothing else, then, this remains an industry where the trajectory from zero to hero and back remains incredibly quick.