condition mean min max ZT0-3 8.407407 8.407407 8.407407 ZT4-7 8.948166 8.948166 8.948166 ZT8-11 8.9526795 8.9526795 8.9526795 ZT12-15 8.279205000000001 8.279205000000001 8.279205000000001 ZT16-19 8.864917 8.864917 8.864917 ZT20-23 8.831132499999999 8.831132499999999 8.831132499999999