elasticsearch 前缀（模糊） 聚合

有以下数据，如何统计 statuscode 中 400（403，404 看做400）和 500（503，505 看做500）的数量？
能用聚合实现最好，不能用聚合其他方式只要能得到预期结果就行。
求大佬们不吝赐教。

[

    {

        "statuscode": "200",

        "method": "GET",

        "reqtime": 4265,

        "url": "http://www.baidu.com/news/2017 ... ot%3B

    },

    {

        "statuscode": "400",

        "method": "GET",

        "reqtime": 29009,

        "url": "http://www.baidu.com/news/2017 ... ot%3B

    },

    {

        "statuscode": "404",

        "method": "get",

        "reqtime": 3632,

        "url": "http://www.baidu.com/"

    },

    {

        "statuscode": "403",

        "method": "GET",

        "reqtime": 4560,

        "url": "http://www.baidu.com/news/2017 ... ot%3B

    },

    {

        "statuscode": "200",

        "method": "GET",

        "reqtime": 9217,

        "url": "http://www.baidu.com/news/2017 ... ot%3B

    },

    {

        "statuscode": "503",

        "method": "GET",

        "reqtime": 3237,

        "url": "http://www.baidu.com/news/2017 ... ot%3B

    },

    {

        "statuscode": "505",

        "method": "GET",

        "reqtime": 29687,

        "url": "http://www.baidu.com/news/2017 ... ot%3B

    },

    {

        "statuscode": "500",

        "method": "GET",

        "reqtime": 39081,

        "url": "http://www.baidu.com/news/2017 ... ot%3B

    },

    {

        "statuscode": "200",

        "method": "GET",

        "reqtime": 11015,

        "url": "http://www.baidu.com/news/2017 ... ot%3B

    },

    {

        "statuscode": "200",

        "method": "GET",

        "reqtime": 11653,

        "url": "http://www.baidu.com/news/2017 ... ot%3B

    }

]

]