condition mean min max ZT0-3 19.561475 17.3344 21.78855 ZT4-7 13.16545 13.16545 13.16545 ZT8-11 11.286 11.286 11.286 ZT12-15 0 0 0 ZT16-19 16.458399999999997 16.458399999999997 16.458399999999997 ZT20-23 18.88865 18.88865 18.88865