More than 2.49 million tourists came to Shanghai during the Spring Festival holiday,a 4.39 percent increase on last year
问题描述：
More than 2.49 million tourists came to Shanghai during the Spring Festival holiday,a 4.39 percent increase on last year.
请教这里的on last year,为什么要加个on呢?
答
a ...increase on...在...基础上/比...增长了多少.意为：今年春节期间上海游客人数比去年增长了4.39个百分点.