Botswana's sharp economic growth was because of built on a foundation of diamond mining, prudent fiscal policies, international financial and technical assistance, and a cautious foreign policy. Botswana's economy is mostly dependent on diamond mining. Diamond mining contributes to 50% of the government revenue. It is the least corrupt country in Africa in the Corruption Perceptions Index by international corruption watchdog Transparency International. It has the fourth highest gross national income per capita in purchasing power in Africa and above the world average.