condition mean min max ZT0-3 8.419345 8.419345 8.419345 ZT4-7 6.851075 6.851075 6.851075 ZT8-11 6.0659849999999995 6.0659849999999995 6.0659849999999995 ZT12-15 5.364789999999999 5.364789999999999 5.364789999999999 ZT16-19 6.95019 6.95019 6.95019 ZT20-23 5.633205 5.633205 5.633205