The Kingdom of Saudi Arabia is an Arab country and the largest country of the Arabian Peninsula. It has an estimated population of 27.6 million, and its size is approximately 2,150,000 square kilometres (830,000 sq mi). Saudi Arabia has an oil-based economy with strong government controls over major economic activities. It possesses more than 20% of the world’s proven petroleum reserves, ranks as the largest exporter of petroleum, and plays a leading role in OPEC. The petroleum sector accounts for roughly 80% of budget revenues, 45% of GDP, and 90% of export earnings. About 40% of GDP comes from the private sector. Roughly 6.4 million foreign workers play an important role in the Saudi economy, particularly in the oil and service sectors. High oil prices through mid-2008 have boosted growth, government revenues, and Saudi ownership of foreign assets, while enabling Riyadh to pay down domestic debt.