condition mean min max ZT0-3 236.620574 236.620574 236.620574 ZT4-7 255.44703099999998 255.44703099999998 255.44703099999998 ZT8-11 272.502788 272.502788 272.502788 ZT12-15 226.7506325 226.7506325 226.7506325 ZT16-19 307.99779650000005 307.99779650000005 307.99779650000005 ZT20-23 284.030354 284.030354 284.030354