condition mean min max ZT0-3 2.21481 2.21481 2.21481 ZT4-7 2.467024 2.467024 2.467024 ZT8-11 1.143442 1.143442 1.143442 ZT12-15 1.57329 1.57329 1.57329 ZT16-19 1.2115445 1.2115445 1.2115445 ZT20-23 1.881995 1.881995 1.881995