condition mean min max ZT0-3 36.12127562 31.15817577 41.08437547 ZT4-7 13.593783365 12.2872707 14.90029603 ZT8-11 20.199858445 14.834674360000001 25.56504253 ZT12-15 23.4728787525 22.460611845 24.48514566 ZT16-19 21.2303141825 20.718582165 21.742046199999997 ZT20-23 18.3029469775 17.41278191 19.193112045