The economic growth of Cuba mainly depends on Tourism, Agriculture, biotechnology and pharmaceutical industry, foreign investment and International Trade. The Cuban Government continues to adhere to socialist principles in organizing its state-controlled economy. Most of the means of production are owned and run by the government. Sugar has its major contribution to the economy's development and the most important exports. Nickel is the country's second most valuable export item (after sugar). Large amounts of copper, chromium, and cobalt are also mined, as well as lesser quantities of salt, lead, zinc, gold, silver, and petroleum. Vaccines in Cuba amounts to a major source as far as foreign exchange is concerned with nations like Russia, China, India, Pakistan, and Latin American countries.