condition mean min max ZT0-3 7.986423 7.986423 7.986423 ZT4-7 7.6234090000000005 7.6234090000000005 7.6234090000000005 ZT8-11 8.541032000000001 8.541032000000001 8.541032000000001 ZT12-15 7.5187745 7.5187745 7.5187745 ZT16-19 7.928891999999999 7.928891999999999 7.928891999999999 ZT20-23 7.9223669999999995 7.9223669999999995 7.9223669999999995