condition mean min max ZT0-3 8.011989 8.011989 8.011989 ZT4-7 9.305793999999999 9.305793999999999 9.305793999999999 ZT8-11 8.631515 8.631515 8.631515 ZT12-15 8.3032465 8.3032465 8.3032465 ZT16-19 8.3555895 8.3555895 8.3555895 ZT20-23 9.299054 9.299054 9.299054