condition mean min max ZT0-3 1858.426287 1858.426287 1858.426287 ZT4-7 1591.904881 1591.904881 1591.904881 ZT8-11 1541.240103 1541.240103 1541.240103 ZT12-15 1995.040821 1995.040821 1995.040821 ZT16-19 1647.060552 1647.060552 1647.060552 ZT20-23 1251.841194 1251.841194 1251.841194