condition mean min max ZT0-3 5.876495 5.876495 5.876495 ZT4-7 6.247695 6.247695 6.247695 ZT8-11 6.22778 6.22778 6.22778 ZT12-15 4.167095 4.167095 4.167095 ZT16-19 3.72011 3.72011 3.72011 ZT20-23 4.964354999999999 4.964354999999999 4.964354999999999