condition mean min max ZT0-3 8.294821 8.294821 8.294821 ZT4-7 10.3057035 10.3057035 10.3057035 ZT8-11 18.120496499999998 18.120496499999998 18.120496499999998 ZT12-15 18.6346115 18.6346115 18.6346115 ZT16-19 15.9762905 15.9762905 15.9762905 ZT20-23 17.6682175 17.6682175 17.6682175