以铜为例：从2001年到2006年，其价格大幅震荡，一些年份下跌30 % ， 另一些年份上涨150 % — —而中国工业产量和铜需求增长均保持相对稳定，分别为15%和20 % 。
Consider copper: From 2001 to 2006, prices gyrated wildly, with price declines of 30% in some years and increases of 150% in others – all while growth in Chinese industrial production and demand for copper remained relatively steady, at 15% and 20%, respectively.