South America's Guyana, a country of 780,000, will experience the world's fastest economic growth in 2020 driven by ExxonMobil's discovery of oil, according to IMF. Its GDP is expected to grow 86% next year after expanding 4.4% this year. Guyana is projecting $300 million in petroleum revenue in 2020 as ExxonMobil starts pumping from its first oil well next month.