condition mean min max ZT0-3 2.123596666666667 1.074055 2.971025 ZT4-7 1.53902 1.53902 1.53902 ZT8-11 1.63016 1.63016 1.63016 ZT12-15 3.1648324999999997 2.602225 3.7274399999999996 ZT16-19 3.3927750000000003 3.3927750000000003 3.3927750000000003 ZT20-23 3.574465 3.574465 3.574465