condition mean min max ZT0-3 14.037685 11.534105 16.16685 ZT4-7 8.22814 8.22814 8.22814 ZT8-11 8.843035 8.843035 8.843035 ZT12-15 20.56445 17.5085 23.6204 ZT16-19 17.24995 17.24995 17.24995 ZT20-23 24.4739 24.4739 24.4739