The pound coin (£1) was introduced in 1983 to replace the Bank of England £1 banknote which was discontinued in 1984 (although the Scottish banks continued producing them for some time afterwards; the last of them, the Royal Bank of Scotland £1 note, is still in production ). The designs on the one pound coin changed annually in a largely five-year cycle, until the introduction of the new 12-sided pound coin in 2017. The decimal half penny coin was demonetised in 1984 as its value was by then too small to be useful. The pre-decimal sixpence, shilling and two shilling coins, which had continued to circulate alongside the decimal coinage with values of p, 5p and 10p respectively, were finally withdrawn in 1980, 1990 and 1993 respectively. However, the double florin and crown with values of 20p and 25p respectively have not been withdrawn. In the 1990s, the Royal Mint reduced the sizes of the 5p, 10p, and 50p coins. As a consequence, the oldest 5p coins in circulation date from 1990, the oldest 10p coins from 1992 and the oldest 50p coins come from 1997. Since 1997, many special commemorative designs of 50p have been issued. Some of these are found fairly frequently in circulation and some are rare. They are all legal tender. The specifications and dates of introduction of the 5p, 10p, and 50p coins refer to the current versions. These coins were originally issued in larger sizes in 1968 and 1969 respectively. With their high copper content (97%), the intrinsic value of pre-1992 1p and 2p coins increased with the surge in metal prices of the mid-2000s, until by 2006 the coins would, if melted down, have been worth about 50% more than their face value. (To do this, however, would be illegal, and they would have had to be melted in huge quantities, using quite a bit of energy, to achieve significant gain.) In later years, the price of copper fell considerably. Copper plated steel coins were introduced to replace them. A circulating bimetallic two pound (£2) coin was introduced in 1998 (first minted in, and dated, 1997). There had previously been unimetallic commemorative £2 coins which did not normally circulate. This tendency to use the two pound coin for commemorative issues has continued since the introduction of the bimetallic coin, and a few of the older unimetallic coins have since entered circulation.