condition mean min max ZT0-3 8.27989 8.27989 8.27989 ZT4-7 9.02835 9.02835 9.02835 ZT8-11 8.425740000000001 8.425740000000001 8.425740000000001 ZT12-15 8.1694675 8.1694675 8.1694675 ZT16-19 7.525313499999999 7.525313499999999 7.525313499999999 ZT20-23 8.129026 8.129026 8.129026