condition mean min max ZT0-3 12.565297 12.565297 12.565297 ZT4-7 12.9216895 12.9216895 12.9216895 ZT8-11 15.304205499999998 15.304205499999998 15.304205499999998 ZT12-15 13.557045500000001 13.557045500000001 13.557045500000001 ZT16-19 14.5618765 14.5618765 14.5618765 ZT20-23 12.321659 12.321659 12.321659