condition mean min max ZT0-3 19.765363 19.765363 19.765363 ZT4-7 23.229775 23.229775 23.229775 ZT8-11 19.509396000000002 19.509396000000002 19.509396000000002 ZT12-15 18.8911035 18.8911035 18.8911035 ZT16-19 16.5582595 16.5582595 16.5582595 ZT20-23 19.568022999999997 19.568022999999997 19.568022999999997