condition mean min max ZT0-3 3.177195 3.177195 3.177195 ZT4-7 2.97142 2.97142 2.97142 ZT8-11 2.5253249999999996 2.5253249999999996 2.5253249999999996 ZT12-15 2.81879 2.81879 2.81879 ZT16-19 3.3728949999999998 3.3728949999999998 3.3728949999999998 ZT20-23 3.18096 3.18096 3.18096