Despite facing challenges at the domestic level along with a rapidly transforming global landscape, the U.S. economy is still the largest and most important in the world. The U.S. economy represents about 20% of total global output, and is still larger than that of China. Moreover, according to the IMF, the U.S. has the sixth highest per capita GDP (PPP), surpassed only by small countries such as Norway and Singapore. The U.S. economy features a highly-developed and technologically-advanced services sector, which accounts for about 80% of its output. The U.S. economy is dominated by services-oriented companies in areas such as technology, financial services, healthcare and retail. Large U.S. corporations also play a major role on the global stage, with more than a fifth of companies on the Fortune Global 500 coming from the United States.