condition mean min max ZT0-3 34.078625 31.1669 36.99035 ZT4-7 17.88525 17.88525 17.88525 ZT8-11 8.80115 8.80115 8.80115 ZT12-15 0 0 0 ZT16-19 24.173000000000002 24.173000000000002 24.173000000000002 ZT20-23 27.98775 27.98775 27.98775