年齢階層別平均年収(赤旗) https://job-change.useful-info.com/2018/05/14/job-changing-information-for-non-regular-employee/%e5%b9%b4%e9%bd%a2%e9%9a%8e%e5%b1%a4%e5%88%a5%e5%b9%b3%e5%9d%87%e5%b9%b4%e5%8f%8e%ef%bc%88%e8%b5%a4%e6%97%97%ef%bc%89/