One of the poorest countries in the world, landlocked Burkina Faso has a high population density, few natural resources, and a fragile soil. Agriculture comprises approximately 35% of total GDP. More than 90% of the country's working population is engaged in agriculture. Principal crops include rice, millet, maize and sorghum. Cotton is the most noteworthy. Livestock, once a major export, has declined. Industry remains dominated by unprofitable government-controlled corporations. Burkina's exploitable natural resources are limited, although deposits of manganese, zinc, limestone, marble, phosphate and gold have attracted the interest of international mining firms. Burkina Faso, supported by the World Bank and IMF, has begun to implement reforms, which have helped it to increase its real GDP growth. Maintenance of its macroeconomic progress depends on continued low inflation, reduction in the trade deficit, and reforms designed to encourage private investment.