condition mean min max ZT0-3 12.15 12.15 12.15 ZT4-7 10.8 10.8 10.8 ZT8-11 6.15 6.15 6.15 ZT12-15 4.4 4.4 4.4 ZT16-19 8.350000000000001 8.350000000000001 8.350000000000001 ZT20-23 20.4 20.4 20.4