As ever, the counter-intuitive nature of the chart, i.e. that Symbian still dominates despite Android and iOS activations reportedly running very high through 2011, is explained by the difference between sales marketshare and installed base 'share'. There are 300 million or so active Symbian users across the world - regardless of whether they're using a three year old Nokia 5800 or even an older N95 - and this is a statistic that can't be ignored for actual use. You may remember that I've talked before about not underestimating the inertia behind Symbian's installed base - the numbers boggle the mind.
Added to the huge installed base of Symbian smartphones is the factor of the rise and rise of affordable data, even on pay as you go SIM cards, across the world. In other words, just about everyone is now getting online!