The official tourist exchange rate for so-called capitalist currencies underwent similar revisions and was set at 1.65 leva per US$1 on February 14, 1973. The noncommercial rate for ruble area countries, based on a parity of 0.78 leva per 1 ruble, was equivalent to 0.64 leva per US$1 until that date; thereafter, at the new ruble-United States dollar parity, it was equivalent to about 0.59 leva per US$1. In addition to the official exchange rates, there are three varieties of clearing account rates. The multilateral transferable ruble is used to clear accounts with other European members of the Council for Mutual Economic Assistance (COMECON--see Glossary). Socialist bilateral units arise from bilateral trade agreements with other communist countries. Neither of these two exchange varieties has private markets abroad. Bilateral clearing units arise from bilateral trade and payments agreements with about thirty noncommunist trading partners. These clearing units are traded sporadically abroad at varying rates of discount. The lev has been traded on the black market in exchange for so-called capitalist banknotes or gold coins. The black market rate of the lev fluctuated between 4.60 leva per US$1 in January 1963 and 2.58 leva per US$1 in June 1972. Except for small remittances or travel allocations to other communist countries, the lev is nontransferable for residents; resident status applies to all physical and juridical persons who have resided in the country for more than six months, regardless of their citizenship. Ownership of or trade in gold, foreign currencies, or so-called capitalist securities is prohibited, as is the import and export of Bulgarian banknotes. There are no investments by noncommunist country nationals in Bulgaria. Exchange transactions are administered by the Bulgarian National Bank jointly with the Ministry of Finance, the Ministry of Foreign Trade, and the Bulgarian Foreign Trade Bank. Bulgaria is neither a member of the International Bank for Reconstruction and Development nor of the International Monetary Fund. Statistics on currency in circulation, the public debt, foreign exchange reserves, gold stocks, and the balance of payments have not been published. FOREIGN TRADE Foreign trade is a state monopoly. Trade policy is formulated by the BKP and government leadership; it is translated into a complex set of laws and regulations designed to encourage the expansion and qualitative improvement of production for export, to promote import substitution, and to bring about greater efficiency in production and foreign trade operations. Control over foreign trade is shared by the Ministry of Foreign Trade, the Ministry of Finance, and the Bulgarian National Bank through the Bulgarian Foreign Trade Bank.