关于学校的保险

最近学校要求需要开始选保险了，于是翻出信件来看看，发现这一句不大懂。
A half-time Graduate Research Associateship appointment provides:
1. (略)
2. (略)
3. Eligibility for subsidized health insurance (currently subsidized at 85%).
这个第三条是说我需要自己交85%保险呢还是说我只需要交15%的保险？多谢各位知情者~

交15%