condition mean min max ZT0-3 6.95657 6.351825 7.7363100000000005 ZT4-7 6.90329 6.90329 6.90329 ZT8-11 5.98935 5.98935 5.98935 ZT12-15 8.3697075 7.607015 9.1324 ZT16-19 7.370875 7.370875 7.370875 ZT20-23 8.671545 8.671545 8.671545