same time it was widely popular and given the endearing nickname of Vreneli. The coin was minted between 1897 and 1949 with a total issue of 58.6 million pieces. A 10 francs version of the coin was produced from 1911 to 1922, with a total issue of 2.6 million. In 1925, 5,000 pieces of a 100 francs version were minted. The first series of banknotes, issued 1907, included no 10 or 20 francs denomination. The gold coins existed in circulation alongside the corresponding banknotes during 1911–1936. With the devaluation of 1936, the gold value of the 20 franc coin rose to 28 francs. In spite of this, production of the 20 francs coin continued until 1949, and the coin has never been officially retired from circulation, even though its gold value has now risen far beyond its nominal value of 20 francs. The pre-1897 versions of the 20 francs coin are very rare. Trial versions were produced in 1871 in two designs at 200 and 30 pieces, respectively, in 1873 in 1,000 and 80 pieces, respectively. A small number of coins was made from gold mined in the Gondo mine (Zwischbergen, Valais): 25 pieces in 1893, 19 pieces in 1895, 29 pieces in 1897. Two additional gold coins, with nominal values of 25 and 50 francs, were planned in the 1950s. The design was chosen in 1954, the 25 francs coin represented William Tell and the 50 francs coin the Rütli oath. A total of 15 and 6 million pieces of the 25 and 50 francs version, respectively, were minted in 1955, 1956 and 1959. However, in the interest of maintaining the national gold reserves, the coins were never given into circulation and remained the property of the Swiss National Bank. In a press release of February 2009, it was made public that all of these coins had been melted back into bars except for a remainder of 20,000 coins of each type and year (for a total of 120,000 surviving pieces). Circulation Since 2004 the pure nickel 20 centime coins of the years 1881–1938 have been withdrawn from circulation because machines cannot detect them. Today, all the coins except the 5 centime coin (aluminium-bronze since 1981) are in a copper-nickel (cupronickel) alloy. Seven coins are currently in circulation: Commemorative coins The federal mint has issued numerous commemorative or collectors' editions of coins. This tradition originates with the Schützentaler of