condition mean min max ZT0-3 8.740818 8.740818 8.740818 ZT4-7 9.5303085 9.5303085 9.5303085 ZT8-11 9.481048000000001 9.481048000000001 9.481048000000001 ZT12-15 11.5041795 11.5041795 11.5041795 ZT16-19 8.8796085 8.8796085 8.8796085 ZT20-23 10.066814 10.066814 10.066814