index number of quantum imports or exports

例句：

1. 1. The index of the stock market has been rising steadily.
   股市的指数一直在稳步上升。
2. 2. The index of the economy is closely watched by economists.
   经济指数是经济学家密切关注的。
3. 3. The index of the company's performance has fallen significantly.
   公司业绩指数大幅下降。