json=$(
  curl -G \
    -d 'format=json' \
    -d 'formatversion=2' \
    -d 'action=wbcheckconstraints' \
    -d 'id=Q64' \
    https://www.wikidata.org/w/api.php
)

withDetail=$(
  printf '%s' "$json" |
  jq -c . |
  wc -c
)

withoutDetail=$(
  printf '%s' "$json" |
  jq -c '
    del(
      .. |
      objects |
      select(has("constraint")) |
      .constraint |
      (.detail, .detailHTML)
    )
  ' |
  wc -c
)

awk \
  -v "withDetail=$withDetail" \
  -v "withoutDetail=$withoutDetail" \
  'END {
    removed = withDetail-withoutDetail
    printf "%2.2f%%\n", 100 * removed / withDetail
  }' < /dev/null