condition mean min max ZT0-3 2.704725936 2.225908961 3.1835429110000004 ZT4-7 3.8969552837499997 3.1558166534999996 4.638093914 ZT8-11 4.31386587275 4.2696448254999995 4.35808692 ZT12-15 5.99580173725 4.687954323 7.3036491515 ZT16-19 6.82093848325 5.485437908 8.1564390585 ZT20-23 13.7761130875 11.494186405 16.05803977