condition mean min max ZT0-3 6.472885 6.472885 6.472885 ZT4-7 6.428364999999999 6.428364999999999 6.428364999999999 ZT8-11 5.34424 5.34424 5.34424 ZT12-15 3.5058049999999996 3.5058049999999996 3.5058049999999996 ZT16-19 6.55481 6.55481 6.55481 ZT20-23 7.401265 7.401265 7.401265