condition mean min max ZT0-3 18.5834 18.5834 18.5834 ZT4-7 16.6859 16.6859 16.6859 ZT8-11 17.30155 17.30155 17.30155 ZT12-15 21.3705 21.3705 21.3705 ZT16-19 18.38915 18.38915 18.38915 ZT20-23 17.586199999999998 17.586199999999998 17.586199999999998