Listing pages and pages of market size numbers that are related to your industry are hard to digest for the novice (for example, a potential investor in your company). This number includes devices, that number is 2011 only, this number excludes Eastern Europe, that one is number of users, that one is in Euro, and this is the percentage growth, but the growth of the average basket size.

An investor who is seriously considering putting money in your company will try to piece this data together to come to some consistent picture. You might as well do the work for her with reasonable assumptions. Size up the 2011 market to 2013, add your estimate for Eastern Europe, convert everything to dollars, etc. etc.

Start with some sort of overall market estimate, compare it to something the investor can relate to, then start adding complexity, break things into pieces.

Obviously your estimate will biased and very optimistic, but your analysis has at least provided the investor with a framework of how to think about your market. Put all the raw data that you used in the appendix so that the investor can do her own homework when she returns back to her office.