condition mean min max ZT0-3 4.050000000000001 4.050000000000001 4.050000000000001 ZT4-7 6.7 6.7 6.7 ZT8-11 8.15 8.15 8.15 ZT12-15 6.65 6.65 6.65 ZT16-19 9.5 9.5 9.5 ZT20-23 5.949999999999999 5.949999999999999 5.949999999999999