condition mean min max ZT0-3 15.663284 15.663284 15.663284 ZT4-7 16.355650999999998 16.355650999999998 16.355650999999998 ZT8-11 16.8522155 16.8522155 16.8522155 ZT12-15 17.418726 17.418726 17.418726 ZT16-19 15.812821 15.812821 15.812821 ZT20-23 13.718840499999999 13.718840499999999 13.718840499999999