The influx of an average 1,000 Somali refugees per month into Yemen looking for work is an added drain on the economy, which already must cope with a 20 to 40 percent rate of unemployment. Yemen remains under significant pressure to implement economic reforms, lest it face the loss of badly needed international financial support. In the north, disruptions of the civil war (1962–1970) and frequent periods of drought dealt severe blows to a previously prosperous agricultural sector. Coffee production, formerly the north's main export and principal form of foreign exchange, declined as the cultivation of khat increased. Low domestic industrial output and a lack of raw materials made the Yemeni Arab Republic dependent on a wide variety of imports. The Yemeni Civil War and air bombing campaign by the coalition during the Saudi-led intervention have devastated the Yemeni economy further. As a result of civil war, Yemen is suffering from inflation and devaluation of Yemeni rial, and Yemen's economy contracted by 50% from the start of the civil war on 19 March 2015 to October 2018. Macro-economic trend This is a chart of trend of gross domestic product of Yemen (since unification) at market prices estimated by the International Monetary Fund with figures in millions of Yemeni Rials. For purchasing power parity comparisons, the US Dollar is exchanged at 150.11 Yemeni Rials only. Mean wages were $1.06 per man-hour in 2009. Remittances from Yemenis working abroad and foreign aid paid for perennial trade deficits. Substantial Yemeni communities exist in many countries of the world, including Yemen's immediate neighbors on the Arabian Peninsula, Indonesia, India, East Africa, the United Kingdom, and the United States. Beginning in the mid-1950s, the Soviet Union and People's Republic of China provided large-scale assistance to the YAR. This aid included funding of substantial construction projects, scholarships, and considerable military assistance. Integration issues In the south, pre-independence economic activity was overwhelmingly concentrated in the port city of Aden. The seaborne transit trade, upon which the port relied, collapsed with the closure of the Suez Canal and Britain's withdrawal from Aden in 1967. Only extensive Soviet aid, remittances from south Yemenis working abroad, and revenues from the Aden refinery (built in the 1950s) kept the PDRY's centrally planned Marxist economy afloat. With the dissolution of the Soviet Union and a cessation of Soviet aid, the south's economy effectively collapsed. Since unification, the government has worked to integrate