The percentage of students who valued the access to sports facilities more than tripled from 5% to 18% in 2001.

参考译文：珍惜利用体育设施的学生百分比在2001从5%到18%增加了3倍多。

解答如下：

句子谓语为：triple，因此不需要在家谓语“is”

vi./vt. (使)变成三倍;(使)增至三倍 (英语解释：If something triples or if you triple it, it becomes three times as large in size or number.）

I got a fantastic new job and my salary tripled.  

我得到了一份非常好的新工作，薪水涨到了原来的 3 倍。

The Exhibition has tripled in size from last year.

展览会规模自去年已经扩至3倍。