condition mean min max ZT0-3 4.072525 4.072525 4.072525 ZT4-7 3.18225 3.18225 3.18225 ZT8-11 2.9459400000000002 2.9459400000000002 2.9459400000000002 ZT12-15 2.308295 2.308295 2.308295 ZT16-19 3.2339 3.2339 3.2339 ZT20-23 3.23881 3.23881 3.23881