condition mean min max ZT0-3 21.689025 21.071550000000002 22.3065 ZT4-7 16.63275 16.63275 16.63275 ZT8-11 19.26665 19.26665 19.26665 ZT12-15 0 0 0 ZT16-19 23.3419 23.3419 23.3419 ZT20-23 26.505699999999997 26.505699999999997 26.505699999999997