condition mean min max ZT0-3 22.967925 20.31195 25.6239 ZT4-7 14.67175 14.67175 14.67175 ZT8-11 15.71715 15.71715 15.71715 ZT12-15 0 0 0 ZT16-19 22.136850000000003 22.136850000000003 22.136850000000003 ZT20-23 28.05155 28.05155 28.05155