condition mean min max ZT0-3 6.210185 2.704145 8.502915 ZT4-7 2.3972949999999997 2.3972949999999997 2.3972949999999997 ZT8-11 2.22308 2.22308 2.22308 ZT12-15 3.6835525000000002 3.512265 3.8548400000000003 ZT16-19 3.97998 3.97998 3.97998 ZT20-23 8.08748 8.08748 8.08748