condition mean min max ZT0-3 18.260035 18.260035 18.260035 ZT4-7 21.445063500000003 21.445063500000003 21.445063500000003 ZT8-11 19.8176515 19.8176515 19.8176515 ZT12-15 35.385429 35.385429 35.385429 ZT16-19 21.481081500000002 21.481081500000002 21.481081500000002 ZT20-23 24.702098 24.702098 24.702098