condition mean min max ZT0-3 6.38618 6.38618 6.38618 ZT4-7 6.3782000000000005 6.3782000000000005 6.3782000000000005 ZT8-11 6.093719999999999 6.093719999999999 6.093719999999999 ZT12-15 6.14572 6.14572 6.14572 ZT16-19 6.219196666666667 6.219196666666667 6.219196666666667 ZT20-23 6.2846400000000004 6.2846400000000004 6.2846400000000004