condition mean min max ZT0-3 20.248036 20.248036 20.248036 ZT4-7 29.8196485 29.8196485 29.8196485 ZT8-11 20.313322999999997 20.313322999999997 20.313322999999997 ZT12-15 25.640769499999998 25.640769499999998 25.640769499999998 ZT16-19 19.021607 19.021607 19.021607 ZT20-23 17.945961 17.945961 17.945961