England's economy is one of the largest in the world, with an average GDP per capita of £22,907.[134] Usually regarded as a mixed market economy, it has adopted many free market principles, yet maintains an advanced social welfare infrastructure.[135] The official currency in England is the pound sterling, whose ISO 4217 code is GBP. Taxation in England is quite competitive when compared to much of the rest of Europe—as of 2009 the basic rate of personal tax is 20% on taxable income up to £37,400, and 40% on any additional earnings above that amount.[136]