Output is now six time what it was before 1990.这里的what是什么意思?

问题描述:

Output is now six time what it was before 1990.这里的what是什么意思?

输出(出口)现在是1990年以前的6倍.
句子有错误,应该是:
Output is now six times of what it was before 1990.
what在句中起引导从句的作用.