condition mean min max ZT0-3 7.412272 7.412272 7.412272 ZT4-7 7.412272 7.412272 7.412272 ZT8-11 8.1875825 8.1875825 8.1875825 ZT12-15 7.182333 7.182333 7.182333 ZT16-19 7.4451160000000005 7.4451160000000005 7.4451160000000005 ZT20-23 6.989831 6.989831 6.989831