condition mean min max ZT0-3 22.743225 21.52875 23.9577 ZT4-7 23.79215 23.79215 23.79215 ZT8-11 31.78295 31.78295 31.78295 ZT12-15 0 0 0 ZT16-19 34.009550000000004 34.009550000000004 34.009550000000004 ZT20-23 28.29105 28.29105 28.29105