这句话里的 leading measure

这句话里的 leading measure The leading measure of Japanese stock prices was up 57 percent last year.That was the best performance for Japan's Nikkei Index in many years.In the United States,another stock index,the S&P 500,rose almost 30 percent in 2013.Another measure of stocks,the NASDAQ Composite Index,rose 38 percent.VOA里翻成日经指数,感觉好奇怪.