condition mean min max ZT0-3 231.153165 231.153165 231.153165 ZT4-7 242.8910945 242.8910945 242.8910945 ZT8-11 226.56435699999997 226.56435699999997 226.56435699999997 ZT12-15 251.154764 251.154764 251.154764 ZT16-19 341.81564249999997 341.81564249999997 341.81564249999997 ZT20-23 312.9898205 312.9898205 312.9898205