condition mean min max ZT0-3 12.403105 7.190465 15.4507 ZT4-7 7.059595 7.059595 7.059595 ZT8-11 7.709175 7.709175 7.709175 ZT12-15 14.491775 14.22565 14.7579 ZT16-19 15.7416 15.7416 15.7416 ZT20-23 19.054000000000002 19.054000000000002 19.054000000000002