prices was and at constant prices was . The domestic product of agriculture sector accounts for and industrial sector for . The service sector of the state accounts more percentage of the GSDP with a total of . In the 2010 list by Forbes magazine, several people from Andhra Pradesh were among the top 100 richest Indians. Agriculture Andhra Pradesh's economy is mainly based on agriculture and livestock. Four important rivers of India, the Godavari, Krishna, Penna, and Tungabhadra flow through the state and provide irrigation. 60 percent of the population is engaged in agriculture and related activities. Rice is the major food crop and staple food of the state. It is an exporter of many agricultural products and is also known as "Rice Bowl of India". The state has three Agricultural Economic Zones in Chittoor district for mango pulp and vegetables, Krishna district for mangoes, Guntur district for chilies. Besides rice, farmers also grow jowar, bajra, maize, minor millet, coarse grain, many varieties of pulses, oil seeds, sugarcane, cotton, chili pepper, mango nuts and tobacco. Crops used for vegetable oil production such as sunflower and peanuts are popular. There are many multi-state irrigation projects under development, including Godavari River Basin Irrigation Projects and Nagarjuna Sagar Dam. Livestock and poultry is also another profitable business, which involves rearing cattle in enclosed areas for commercial purposes. The state is also a largest producer of eggs in the country and hence, it is nicknamed as "Egg Bowl of Asia". Fisheries contribute 10% of total fish and over 70% of the shrimp production of India. The geographical location of the state allows marine fishing as well as inland fish production. The most exported marine exports include Vannamei shrimp Infrastructure Andhra Pradesh is investing in building infrastructure in the state such as highways and making every service of the government digital. National Highway 16 passes through Andhra Pradesh. The highways in the state are also being widened. APSFL is an initiative of the government of Andhra Pradesh to set up an optical fiber network throughout the thirteen districts of Andhra Pradesh. This network provides internet connectivity, telephony and IPTV with fiber to private and corporate users of Andhra Pradesh. The state also has seaports such as Visakhapatnam Port, Kakinada Port, Krishnapatnam Port for import and export and a shipyard for building ships at Visakhapatnam. Major airports in the state are Visakhapatnam, Rajahmundry, Vijayawada, with