Vega Line and Bar chart

{
  "width": 500,
  "height": 200,
  "padding": {"top": 10, "left": 30, "bottom": 30, "right": 10},
  "data": [
    {
      "name": "table",
      "values": [
        {"x": 1,  "y": 28, "z" : 13}, {"x": 2,  "y": 55, "z" : 21},
        {"x": 3,  "y": 43, "z" : 52}, {"x": 4,  "y": 91, "z" : 12}
      ]
    }
  ],
  "scales": [
    {
      "name": "x",
      "type": "linear",
      "range": "width",
      "zero": false,
      "domain": {"data": "table", "field": "x"}
    },
    {
      "name": "y",
      "type": "linear",
      "range": "height",
      "nice": true,
      "domain": {"data": "table", "field": ["y","z"]}
    }
  ],
  "axes": [
    {"type": "x", "scale": "x", "ticks": 20},
    {"type": "y", "scale": "y"}
  ],
  "marks": [
    {
      "type": "line",
      "from": {"data": "table"},
      "properties": {
        "enter": {
          "interpolate": {"value": "monotone"},
          "x": {"scale": "x", "field": "x"},
          "y": {"scale": "y", "field": "y"},
          "y2": {"scale": "y", "value": 0},
          "stroke": { "value": "orange"}
        },
        "update": {
          "fillOpacity": {"value": 1}
        },
        "hover": {
          "fillOpacity": {"value": 0.5}
        }
      }
    },
  {
      "type": "rect",
      "from": {"data": "table"},
      "properties": {
        "enter": {
          "x": {"scale": "x", "field": "x"},
          "width": {"value": 12},
          "y": {"scale": "y", "field": "z"},
          "y2": {"scale": "y", "value": 0},
          "fill": {"value": "steelblue"}
        }
      }
    }
  ]
}