Streamgraph

{
  "$schema": "https://vega.github.io/schema/vega-lite/v2.json",
  "width": 300, "height": 200,
  "data": {"url": "data/unemployment-across-industries.json"},
  "mark": "area",
  "encoding": {
    "x": {
      "timeUnit": "yearmonth", "field": "date", "type": "temporal",
      "axis": {"domain": false, "format": "%Y", "tickSize": 0}
    },
    "y": {
      "aggregate": "sum", "field": "count","type": "quantitative",
      "axis": null,
      "stack": "center"
    },
    "color": {"field":"series", "type":"nominal", "scale":{"scheme": "category20b"}}
  }
}