The Omani economy is a diverse one with services contributing 57 percent of GDP and industry contributing approximately 40 percent. However, over the past 40 years there has been a major shift in the structure of the economy. In the 1950s and 1960s, when the oil fields had not yet been discovered, the agricultural sector drove the economy. This sector has diminished in importance since the early 1970s, representing only 3 percent of GDP in 1999, whereas the export of oil and petroleum-related products and the manufacturing of goods such as textiles has increased. The sector's output is heavily dependent upon the weather, and accurate figures on employment in agriculture remain unknown.