condition mean min max ZT0-3 19.442785 19.442785 19.442785 ZT4-7 24.6297275 24.6297275 24.6297275 ZT8-11 33.2837085 33.2837085 33.2837085 ZT12-15 28.255353 28.255353 28.255353 ZT16-19 25.724487500000002 25.724487500000002 25.724487500000002 ZT20-23 18.786167 18.786167 18.786167