condition mean min max ZT0-3 19.998625 19.190350000000002 20.8069 ZT4-7 17.19945 17.19945 17.19945 ZT8-11 16.1764 16.1764 16.1764 ZT12-15 0 0 0 ZT16-19 21.37725 21.37725 21.37725 ZT20-23 19.70095 19.70095 19.70095