It's the contract,
While the stats about smartphone OS are interesting, an important influence is the nature of the contracts offered in each country. For example in Canada the iPhone is offered only with an expensive multi-year contract including a high-use data plan. If you get an iPhone, you're certainly going to use it for browsing! Blackberry and Android phones are available cheap, without a contract, and can be used on low-limit data plans for the more cost-conscious.