condition mean min max ZT0-3 13.9 13.9 13.9 ZT4-7 13.8 13.8 13.8 ZT8-11 6.949999999999999 6.949999999999999 6.949999999999999 ZT12-15 8.45 8.45 8.45 ZT16-19 21.15 21.15 21.15 ZT20-23 23.85 23.85 23.85