condition mean min max ZT0-3 2.255485 2.255485 2.255485 ZT4-7 1.248215 1.248215 1.248215 ZT8-11 1.0327695 1.0327695 1.0327695 ZT12-15 1.4836399999999998 1.4836399999999998 1.4836399999999998 ZT16-19 4.27307 4.27307 4.27307 ZT20-23 2.70327 2.70327 2.70327