condition mean min max ZT0-3 12.4 12.4 12.4 ZT4-7 5.6 5.6 5.6 ZT8-11 9.7 9.7 9.7 ZT12-15 17.1 17.1 17.1 ZT16-19 8.350000000000001 8.350000000000001 8.350000000000001 ZT20-23 9.5 9.5 9.5