soum to the US dollar increased only by a factor of 1.33, from 969 soum to around 1,865 soum in May 2012. From 1996 until the spring of 2003, the official and so-called "commercial" exchange rate – both set administratively by the Central Bank – were highly overvalued. Many businesses and individuals were unable to buy dollars legally at these "low" rates, so a widespread black market developed to meet hard currency demand. The spread between the official exchange rate and the curb rate widened especially after the Russian financial crisis of August 1998: at the end of 1999 the curb rate stood at 550 soum/US$ compared with the official rate of 140 soum/US$, a gap by nearly a factor of 4 (up from a factor of "only" 2 in 1997 and the first half of 1998). By mid-2003, the government's stabilization and liberalization efforts had reduced the gap between the black market, official, and commercial rates to approximately 8% and it quickly disappeared as the soum was made convertible after October 2003. Today, four foreign currencies—the U.S. dollar, the euro, the pound sterling, and the yen—are freely exchanged in commercial booths all around the cities, while other currencies, including the Russian rouble and the Kazakh tenge, are bought and sold by individual ("black market") money changers, who are allowed to operate openly without harassment. The foreign exchange regime since October 2003 is characterized as "controlled floating rate". Liberalization of the trade regime remains a prerequisite for Uzbekistan to proceed to an IMF-financed program. In 2012, "black market" rate is again significantly higher than official rate, 2,850 soum/US$ vs. 1,865 soum/US$ (as of mid-June 2011). This curb rate is often referred to as 'bazar rate', because money changers operate at or near 'bazars' - large farmer markets. Tax collection rates remained high, due to the use of the banking system by the government as a collection agency. Technical assistance from the World Bank, Office of Technical Assistance at the U.S. Treasury Department, and UNDP is being provided in reforming the Central Bank and Ministry of Finance into institutions capable of conducting market-oriented fiscal and monetary policy. Agriculture In 2018, Uzbekistan produced: 5.4 million tonnes of wheat; 2.9 million tons of potato; 2.2 million tons of cotton (8th largest producer in the world); 2.2 million tons of tomato (14th largest producer in the world); 2.1 million tonnes of carrot (2nd largest