condition mean min max ZT0-3 20.681341 20.681341 20.681341 ZT4-7 30.8119175 30.8119175 30.8119175 ZT8-11 25.2460145 25.2460145 25.2460145 ZT12-15 23.168595500000002 23.168595500000002 23.168595500000002 ZT16-19 19.7893285 19.7893285 19.7893285 ZT20-23 20.75202 20.75202 20.75202