condition mean min max ZT0-3 3.742295 3.742295 3.742295 ZT4-7 2.196875 2.196875 2.196875 ZT8-11 2.868245 2.868245 2.868245 ZT12-15 4.520015 4.520015 4.520015 ZT16-19 5.32882 5.32882 5.32882 ZT20-23 4.334955 4.334955 4.334955