I'd argue that you're using the wrong statistics. You should also take into account the average cost per mobile phone when determining the size of a market. If

I'd argue that you're using the wrong statistics. You should also take into account the average cost per mobile phone when determining the size of a market. If the US market is 3X smaller than China's (by volume), but spends 3X more for each phone, then the markets are roughly equivalent in the terms that a company would care about: profits.