condition mean min max ZT0-3 7.926331 7.926331 7.926331 ZT4-7 8.295080500000001 8.295080500000001 8.295080500000001 ZT8-11 8.9398285 8.9398285 8.9398285 ZT12-15 8.537980000000001 8.537980000000001 8.537980000000001 ZT16-19 9.008346 9.008346 9.008346 ZT20-23 9.940387000000001 9.940387000000001 9.940387000000001