另一方面，人口老龄化速度加快、社会保险福利费水平刚性上升以及部分积累制改革必须应对的隐形债务问题使社保基金的支出量迅速增加；
On the other hand , expenditure of social security funds is rapidly increased by the fast pace of population aging , upgrading of social welfare funds and invisible debt problems to be solved in reforms of partial accumulative system .
福利刚性