condition mean min max ZT0-3 17.511566 17.511566 17.511566 ZT4-7 13.8096055 13.8096055 13.8096055 ZT8-11 11.587464 11.587464 11.587464 ZT12-15 11.172731500000001 11.172731500000001 11.172731500000001 ZT16-19 8.785301 8.785301 8.785301 ZT20-23 9.8729725 9.8729725 9.8729725