貌似从1995才开始有该项指标记录

Attached is the file which contains infomation you need from 1997 to 2010 (pg 4), maybe you could find further information before 1997 from http://www.oecd-ilibrary.org/sites/factbook-2011-en/08/01/01/index.html?itemId=/content/chapter/factbook-2011-68-en.

It's a indirect information (as % of GDP), if you need specific number of R&D, you need to find info of China past decades GDP.

Hope this will help you and best luck for your final report.