condition mean min max ZT0-3 3.974965 3.974965 3.974965 ZT4-7 5.608745 5.608745 5.608745 ZT8-11 4.285145 4.285145 4.285145 ZT12-15 2.940405 2.940405 2.940405 ZT16-19 3.37115 3.37115 3.37115 ZT20-23 2.98846 2.98846 2.98846