condition mean min max ZT0-3 7.653876666666667 6.3479849999999995 8.556280000000001 ZT4-7 5.7574 5.7574 5.7574 ZT8-11 4.8047450000000005 4.8047450000000005 4.8047450000000005 ZT12-15 8.0908 7.180125 9.001475 ZT16-19 6.74536 6.74536 6.74536 ZT20-23 9.060175000000001 9.060175000000001 9.060175000000001