condition mean min max ZT0-3 15.302294 15.302294 15.302294 ZT4-7 15.2875425 15.2875425 15.2875425 ZT8-11 17.625045999999998 17.625045999999998 17.625045999999998 ZT12-15 17.97953 17.97953 17.97953 ZT16-19 13.0252885 13.0252885 13.0252885 ZT20-23 13.2354035 13.2354035 13.2354035