condition mean min max ZT0-3 15.058323 15.058323 15.058323 ZT4-7 17.560996000000003 17.560996000000003 17.560996000000003 ZT8-11 20.90155 20.90155 20.90155 ZT12-15 22.147880999999998 22.147880999999998 22.147880999999998 ZT16-19 20.748448 20.748448 20.748448 ZT20-23 23.4977425 23.4977425 23.4977425