condition mean min max ZT0-3 4.24507 4.24507 4.24507 ZT4-7 3.30392 3.30392 3.30392 ZT8-11 3.6558900000000003 3.6558900000000003 3.6558900000000003 ZT12-15 5.1227599999999995 5.1227599999999995 5.1227599999999995 ZT16-19 5.733316666666666 5.733316666666666 5.733316666666666 ZT20-23 6.37045 6.37045 6.37045