condition mean min max ZT0-3 1.9988861666666666 1.2418035 2.830705 ZT4-7 1.468831 1.468831 1.468831 ZT8-11 1.2971300000000001 1.2971300000000001 1.2971300000000001 ZT12-15 1.4724949999999999 1.2280799999999998 1.71691 ZT16-19 1.009504 1.009504 1.009504 ZT20-23 1.767805 1.767805 1.767805