condition mean min max ZT0-3 6.692345 6.529540000000001 6.85515 ZT4-7 4.079475 4.079475 4.079475 ZT8-11 5.513835 5.513835 5.513835 ZT12-15 0 0 0 ZT16-19 6.336475 6.336475 6.336475 ZT20-23 6.617325 6.617325 6.617325