condition mean min max ZT0-3 9.138912 9.138912 9.138912 ZT4-7 8.6970925 8.6970925 8.6970925 ZT8-11 9.3235095 9.3235095 9.3235095 ZT12-15 8.565190999999999 8.565190999999999 8.565190999999999 ZT16-19 9.7102185 9.7102185 9.7102185 ZT20-23 9.3603255 9.3603255 9.3603255