text: #standardSQL
  # Sites using sr-only or visually-hidden classes
  SELECT
    client,
    COUNT(0) AS total_sites,
    COUNTIF(uses_sr_only) AS sites_with_sr_only,
    COUNTIF(uses_sr_only) / COUNT(0) AS pct_sites_with_sr_only
  FROM (
    SELECT
      _TABLE_SUFFIX AS client,
      CAST(JSON_EXTRACT_SCALAR(JSON_EXTRACT_SCALAR(payload, '$._a11y'), '$.screen_reader_classes') AS BOOL) AS uses_sr_only
    FROM
      `httparchive.pages.2020_08_01_*`
  )
  GROUP BY
    client
  