History of Latvia forests were another export revenue source. On March 27, 1919 the Latvian rublis was introduced with an exchange rate of 1 Latvian rublis equal to 1 ostruble, 2 German marks and 1,5 czar rubles. On March 18, 1920 Latvian rublis was made the only legal currency. Due to high inflation, the new Latvian lats currency was introduced at a rate 1 lat to 50 rublis. In 1923 the Bank of Latvia was established and lats replaced rublis in 1925. Between 1923 and 1930 state budget was with a surplus. On average 25,5% went to defense, 11,2% to education and 23,4%
Currency mostly paper, but Australia's Commonwealth Scientific and Industrial Research Organisation developed the world's first polymer currency in the 1980s that went into circulation on the nation's bicentenary in 1988. Now used in some 22 countries (over 40 if counting commemorative issues), polymer currency dramatically improves the life span of banknotes and prevents counterfeiting. Currency use is based on the concept of lex monetae; that a sovereign state decides which currency it shall use. Currently, the International Organization for Standardization has introduced a three-letter system of codes (ISO 4217) to define currency (as opposed to simple names or currency signs), in