Switzerland has a stable, prosperous and high-tech economy and enjoys great wealth, being ranked as the wealthiest country in the world per capita in multiple rankings. In 2011 it was ranked as the wealthiest country in the world in per capita terms (with "wealth" being defined to include both financial and non-financial assets), while the 2013 Credit Suisse Global Wealth Report showed that Switzerland was the country with the highest average wealth per adult in 2013. It has the world's nineteenth largest economy by nominal GDP and the thirty-sixth largest by purchasing power parity. It is the twentieth largest exporter, despite its small size. Switzerland has the highest European rating in the Index of Economic Freedom 2010, while also providing large coverage through public services. The nominal per capita GDP is higher than those of the larger Western and Central European economies and Japan. If adjusted for purchasing power parity, Switzerland ranks 8th in the world in terms of GDP per capita, according to the World Bank and IMF (ranked 15th according to the CIA Worldfactbook).

Answer this question, if possible (if impossible, reply "unanswerable"): How does the Swiss economy rank worldwide by purchasing power parity?
thirty-sixth largest