以下是我拥有的JSON格式的数据。值将相加 每个月最多一次，并按年份分组，以获取正确的格式来绘制折线图。

const listItems = [{
        "id": 1,"total": 21.15,"dat": "2017-10-21T08:32:36.000Z"
      },{
        "id": 2,"total": 22,"dat": "2018-04-24T13:46:16.000Z"
      },{
        "id": 3,"total": 11,"dat": "2017-11-24T13:46:16.000Z"
      },{
        "id": 4,"total": 12,"dat": "2018-04-02T09:15:35.000Z",}
    ]

我想将其转换为以下格式，以将其绘制在折线图上。是每个月2017年和2018年的两年比较。

var xAxis = {
      categories: [
        "Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"
      ]
    };
    var series = [
      {
        name: "2017",data: [
          7.0,6.9,9.5,14.5,18.2,21.5,25.2,26.5,23.3,18.3,13.9,9.6
        ]
      },{
        name: "2018",data: [-0.2,0.8,5.7,11.3,17.0,22.0,24.8,24.1,20.1,14.1,8.6,2.5
        ]
      }
    ];