condition mean min max ZT0-3 2.856865 2.856865 2.856865 ZT4-7 1.53498 1.53498 1.53498 ZT8-11 2.77576 2.77576 2.77576 ZT12-15 0.67331 0.67331 0.67331 ZT16-19 1.3438405 1.3438405 1.3438405 ZT20-23 2.211605 2.211605 2.211605