condition mean min max ZT0-3 8.782575 8.782575 8.782575 ZT4-7 8.6235915 8.6235915 8.6235915 ZT8-11 8.162755 8.162755 8.162755 ZT12-15 10.174497500000001 10.174497500000001 10.174497500000001 ZT16-19 8.510766 8.510766 8.510766 ZT20-23 9.576761999999999 9.576761999999999 9.576761999999999