Small amounts of radium were still extracted from uranium ore by this method of mixed precipitation and ion exchange as late as the 1990s, but today they are extracted only from spent nuclear fuel. In 1954, the total worldwide supply of purified radium amounted to about and it is still in this range today, while the annual production of pure radium compounds is only about 100 g in total today. The chief radium-producing countries are Belgium, Canada, the Czech Republic, Slovakia, the United Kingdom, and Russia. The amounts of radium produced were and are always relatively small; for example, in 1918, 13.6 g of radium were produced in the United States. The metal is isolated by reducing radium oxide with aluminium metal in a vacuum at 1200 °C.