condition mean min max ZT0-3 4.751358333333334 3.80072 5.862970000000001 ZT4-7 1.94366 1.94366 1.94366 ZT8-11 4.5952850000000005 4.5952850000000005 4.5952850000000005 ZT12-15 6.508815 6.1882649999999995 6.829365 ZT16-19 6.5651150000000005 6.5651150000000005 6.5651150000000005 ZT20-23 8.01067 8.01067 8.01067