More than a quarter of the world's proven oil reserves lie beneath the sands and offshore waters of Saudi Arabia. The discovery of these reserves and the building of the necessary facilities to make possible their use over the past half century and more, have made Saudi Arabia the largest exporter of oil and natural gas liquids in the world. This has enabled the Kingdom to bring about one of the greatest physical transformations achieved by any nation in such a short time. With the introduction of the first five-year development plan in 1970, Saudi Arabia has spent approximately 900 billion U.S. dollars, generated largely through the sale of oil and its products, to establish a sophisticated infrastructure and modern educational, health and other facilities. The existence of such vast hydrocarbon deposits within its territory has bestowed on Saudi Arabia a unique role. In response, the Kingdom has adopted an energy policy based on a commitment to maintain stability in world markets.