It’s been a couple of months since I took a look at the figures released by AdMob on the number of ads served to mobile devices. It was worth taking a break – as I predicted in my previous article, the number of ads served actually fell in February. The January numbers showed spectacular growth, but that was something of an anomaly, a blip driven by the large number of devices coming online after the Christmas period.

So if we compare the numbers for March with those for January, we see a growth of 9.6% - but since January saw a spike, perhaps a more meaningful comparison is with December 2009. That gives an increase of a remarkable 45% overall, in the space of just three months, but as with all statistics, you have to look beyond the headline figures – and in this case, the picture changes. The numbers above refer to the growth in mobile ads worldwide – according to AdMob, some 16.7 billion ads were served in March around the globe. But there are significant regional variations.

Take the North American market, where 8.2 billion ads were served in March. That makes it the single biggest market in the world, with 49% of the worldwide total – but growth since December was 'only' 39.7%. That’s still a spectacular increase; if that quarterly rate is sustained, then March 2011 will see 31 billion ads served in North America alone, almost double the number served to the entire world in March 2010. The European market is also growing – but the powerhouse behind the increasing numbers is Asia. The total number of ads is only half that for North America - but growth over the quarter was an explosive 72%. If that is sustained, then this time next year Asia will overtake North America as the largest market, with an astonishing 36 billion ads.

Of course, all of this is speculation, and shouldn't be relied upon. The increasing number of phones based on Google's Android OS may have an effect, along with the 3G-enabled iPad and the iPhone 4G. It also remains to be seen at what point the North American market becomes sated, while demand in China may still be ramping up. Looking at it from a marketing perspective, any multi-national company planning a campaign which incorporates mobile ads needs to be paying attention to just how big the Asian market is becoming. You can find the AdMob reports here.

AdMob, the company which places ads on websites targeted at mobile users and which has just been acquired by Google, has published the results of a survey into app downloading, buying and usage habits. While the survey was quite small – under 1,000 people who opted-in to the survey – the findings were interesting. iPhone and Android users both downloaded just under 9 apps per month on average, but both were outdone by iPod Touch users, who averaged 12 apps per month.  And those iPod apps also get more use; an average of 100 minutes per user per day, compared to 80 minutes for iPhone and Android.

When it comes to actually paying for apps, Android users average just over one app per month, with only 21% of users buying anything; iPod Touch users average 1.6 apps per month, while the iPhone leads the way with 1.8 – and with 50% of users buying at least one app per month.

The number of ads served by AdMob continues to grow at an astonishing rate; in January, over 7.3 billion ads were served in North America, a jump of a third over December 2009. That rate of growth may slow in the coming months – all those Christmas presents are sure to have caused a spike in January demand and usage, which will likely drop off a little in February. The iPhone and iPod Touch accounted for a whopping 40% of those ads.

What does all this mean? It’s a good indication that the apparently insatiable appetite for apps shows no sign of slowing, and that the rise of the smartphone has yet to get anywhere near a peak. The marketing opportunities presented by providing branded apps, or by using mobile advertising, are ones that companies ignore at their peril. You can find the AdMob reports here.