condition mean min max ZT0-3 13.657176666666667 6.02253 17.57855 ZT4-7 6.489179999999999 6.489179999999999 6.489179999999999 ZT8-11 6.302595 6.302595 6.302595 ZT12-15 8.872937499999999 7.289415 10.45646 ZT16-19 11.27925 11.27925 11.27925 ZT20-23 18.58315 18.58315 18.58315