text: #standardSQL
  # 10_16: <h1> length
  SELECT
    percentile,
    client,
    APPROX_QUANTILES(LENGTH(h1), 1000)[OFFSET(percentile * 10)] AS h1_length
  FROM (
    SELECT
      client,
      REGEXP_EXTRACT(body, '(?i)<h1>([^(</h1>)]*)</h1>') AS h1
    FROM
      `httparchive.almanac.summary_response_bodies`
    WHERE
      date = '2019-07-01' AND
      firstHtml),
    UNNEST([10, 25, 50, 75, 90]) AS percentile
  GROUP BY
    percentile,
    client
  ORDER BY
    percentile,
    client
  