condition mean min max ZT0-3 8.381146 8.381146 8.381146 ZT4-7 7.9333 7.9333 7.9333 ZT8-11 7.64403 7.64403 7.64403 ZT12-15 8.5404975 8.5404975 8.5404975 ZT16-19 7.5217875 7.5217875 7.5217875 ZT20-23 8.0475835 8.0475835 8.0475835