condition mean min max ZT0-3 18.068708 18.068708 18.068708 ZT4-7 13.8090475 13.8090475 13.8090475 ZT8-11 15.102719 15.102719 15.102719 ZT12-15 13.490860000000001 13.490860000000001 13.490860000000001 ZT16-19 15.783983500000001 15.783983500000001 15.783983500000001 ZT20-23 14.4558155 14.4558155 14.4558155