As of 2005, Azerbaijan produced a range of metals and industrial minerals, including aluminum, lead, iron, and zinc. Azerbaijan's importance as a world mineral producer, however, was based on its petroleum extracting industry. The country has been a significant oil producer for more than a century, but recent focus has been on developing offshore resources in the Caspian Sea. Production from the country’s Soviet-era fields are in decline, but since independence, foreign direct investment in offshore fields had revitalized the oil sector through the development of large-scale new projects and the refurbishment of older ones. In 2005, Azerbaijan had signed more than 20 major agreements to develop oilfields with approximately 30 companies from 15 countries.