condition mean min max ZT0-3 7.502826 7.502826 7.502826 ZT4-7 7.4375275 7.4375275 7.4375275 ZT8-11 7.1886925 7.1886925 7.1886925 ZT12-15 7.5745695 7.5745695 7.5745695 ZT16-19 7.3832325 7.3832325 7.3832325 ZT20-23 7.402127999999999 7.402127999999999 7.402127999999999