condition mean min max ZT0-3 3.713915 3.713915 3.713915 ZT4-7 3.2332349999999996 3.2332349999999996 3.2332349999999996 ZT8-11 1.9293900000000002 1.9293900000000002 1.9293900000000002 ZT12-15 2.423555 2.423555 2.423555 ZT16-19 3.7721 3.7721 3.7721 ZT20-23 3.101465 3.101465 3.101465