condition mean min max ZT0-3 11.741275 9.91975 13.5628 ZT4-7 15.313400000000001 15.313400000000001 15.313400000000001 ZT8-11 18.32575 18.32575 18.32575 ZT12-15 0 0 0 ZT16-19 19.633650000000003 19.633650000000003 19.633650000000003 ZT20-23 20.34695 20.34695 20.34695