Bhutan has an agricultural based economy, employing more than 60 of the workforce. The small scale subsistence farming includes rice, corn, root crops, citrus fruit, barley, wheat etc. Wood and leather products, processed foods, alcoholic beverages, calcium carbide, textiles, and handicrafts are also important. Fuels, grain, aircraft, machinery, vehicles, and fabrics are the major imports whereas cardamom and other spices, gypsum, timber, handicrafts, fruit, and precious stones are the primary exports. Hydroelectric power is a most important resource, with some electricity being exported to India. Tourism is a significant though restricted activity, and it is the country's largest source of foreign exchange. Bhutan's economy is closely tied to that of India, both through trade and monetary links. A large number of Bhutan tenders and RFP's float from Consultancy, Education, Health and Social Work Services.