Cumulative Frequency Distribution

{
  "$schema": "https://vega.github.io/schema/vega-lite/v2.json",
  "data": {"url": "data/movies.json"},
  "transform": [{
    "sort": [{"field": "IMDB_Rating"}],
    "window": [{"op": "count", "field": "count", "as": "cumulative_count"}],
    "frame": [null, 0]
  }],
  "mark": "area",
  "encoding": {
    "x": {
      "field": "IMDB_Rating",
      "type": "quantitative"
    },
    "y": {
      "field": "cumulative_count",
      "type": "quantitative"
    }
  }
}