Research on the Contribution Rate Level and Adjustment of China's Social Insurance System 并列题名：Research on the Contribution Rate Level and Adjustment of China's Social Insurance System Research on the optimization of rural social endowment insurance system Research on the distribution effect of China's fiscal and taxation system Research on the optimization and development of agricultural insurance system in China Studies on the contribution regimes of urban employees' basic old-age insurance system Research on the welfare distributional effects of China's social medical insurance system research on the construction of animation performance system