condition mean min max ZT0-3 9.427749 9.427749 9.427749 ZT4-7 8.863294 8.863294 8.863294 ZT8-11 8.004126 8.004126 8.004126 ZT12-15 7.995777500000001 7.995777500000001 7.995777500000001 ZT16-19 8.4403925 8.4403925 8.4403925 ZT20-23 7.5736574999999995 7.5736574999999995 7.5736574999999995