condition mean min max ZT0-3 5.161841666666667 4.331825 5.886975 ZT4-7 3.485485 3.485485 3.485485 ZT8-11 4.1511700000000005 4.1511700000000005 4.1511700000000005 ZT12-15 2.9928 2.379915 3.6056850000000003 ZT16-19 2.920345 2.920345 2.920345 ZT20-23 5.963520000000001 5.963520000000001 5.963520000000001