Algeria figures as one of Africa's wealthiest nations. The hydrocarbons sector is the backbone of the economy, accounting for roughly 60% of budget revenues, 30% of GDP, and over 95% of export earnings. Real GDP has risen due to higher oil output and increased government spending. Algeria has the eighth-largest reserves of natural gas in the world and is the fourth-largest gas exporter; it ranks 15th in oil reserves. Agriculture also plays a strong role in the economy, but due to low productivity, foodstuffs have to be imported. The country's leading industries include food and beverage processing, (notably olive oil and wine), petrochemicals, and light manufacturing. The principal food crops include grains, vegetables, and fruits. Sheep and cattle are the principal livestock, and fishing also plays an important role.