condition mean min max ZT0-3 15.33735 15.33735 15.33735 ZT4-7 7.903075 7.903075 7.903075 ZT8-11 6.2972649999999994 6.2972649999999994 6.2972649999999994 ZT12-15 6.445545 6.445545 6.445545 ZT16-19 12.98025 12.98025 12.98025 ZT20-23 17.811999999999998 17.811999999999998 17.811999999999998