condition mean min max ZT0-3 4.858981666666667 4.083505 5.574655 ZT4-7 3.554495 3.554495 3.554495 ZT8-11 2.7663200000000003 2.7663200000000003 2.7663200000000003 ZT12-15 4.827415 4.54995 5.10488 ZT16-19 4.2533449999999995 4.2533449999999995 4.2533449999999995 ZT20-23 6.064595000000001 6.064595000000001 6.064595000000001