condition mean min max ZT0-3 13.121894 13.121894 13.121894 ZT4-7 15.629929 15.629929 15.629929 ZT8-11 16.978 16.978 16.978 ZT12-15 19.463482999999997 19.463482999999997 19.463482999999997 ZT16-19 19.761961 19.761961 19.761961 ZT20-23 17.630815 17.630815 17.630815