condition mean min max ZT0-3 28.6 28.6 28.6 ZT4-7 6.8 6.8 6.8 ZT8-11 8.8 8.8 8.8 ZT12-15 11.2 11.2 11.2 ZT16-19 6.199999999999999 6.199999999999999 6.199999999999999 ZT20-23 50.1 50.1 50.1