condition mean min max ZT0-3 18.209216666666666 17.66005 19.03015 ZT4-7 13.05185 13.05185 13.05185 ZT8-11 6.10876 6.10876 6.10876 ZT12-15 7.1027175 7.099114999999999 7.10632 ZT16-19 6.0828050000000005 6.0828050000000005 6.0828050000000005 ZT20-23 11.6976 11.6976 11.6976