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8-4. Add the first statistics source

Statistics sources are added from their own tab, not alongside the display data.

  1. On the World Cover 2021 with statistics layer card, open Data Sources and select the Statistics tab.

    Statistics tab highlighted in the layer Data Sources section

  2. Click Add statistics source, choose FlatGeoBuf, and enter the NUTS level 0 (country) source details:

    Add Statistics Source button highlighted on the empty Statistics tab

!!! note "Supported formats" Statistics sources must be FlatGeoBuf or GeoJSON. FlatGeoBuf is preferred: it is indexed, so the Explorer only downloads the features in view.

  • File URL:

    https://esa-apex.s3.eu-west-1.amazonaws.com/APEX-example-data/HI-RES-NUTS/stats.esa_worldcover_2021.nuts_2024.epsg4326.level00.fgb

  • level: Leave it at the pre-filled 0 — this is the first statistics source on the layer, with the coarsest boundaries.

  • zIndex: Leave it at 100, above the display data so the clickable boundaries sit on top of the raster.

  1. Save the source. It now appears under Statistics, separately from the WMS source on the Data tab.

  2. View the result. Open the Preview, turn the layer on, then:

  • Select the Statistics tab in the info panel.
  • Click on a country on the map.

You should see the land cover breakdown for that whole country. If you want to view statistics for another country, select the red Clear link on the statistics panel (top right) and click on another.

Statistics tab showing the World Cover class breakdown for Italy at NUTS level 0

By the way, if you click on France and notice it zooming out to the world, that's not an error. The polygon for France includes its overseas territories, such as French Guiana just north of Brazil - home of Europe's Spaceport

!!! warning "Coordinate reference system"

These files are published in EPSG:4326, matching the `epsg4326` in the file name. Statistics features must be in a CRS the Explorer can reproject to the map — a mismatch shows as boundaries in the wrong place, or no clickable features at all. If you are working with statistics files in future that are in different Coordinate Reference Systems, then you may need to add them as custom statistics. See Tutorial 11.

Did you remember to export?