condition mean min max ZT0-3 7.199999999999999 7.199999999999999 7.199999999999999 ZT4-7 3.2 3.2 3.2 ZT8-11 17.7 17.7 17.7 ZT12-15 7.6499999999999995 7.6499999999999995 7.6499999999999995 ZT16-19 9.8 9.8 9.8 ZT20-23 8.0 8.0 8.0