condition mean min max ZT0-3 9.260385 9.260385 9.260385 ZT4-7 6.470505 6.470505 6.470505 ZT8-11 7.423135 7.423135 7.423135 ZT12-15 9.76934 9.76934 9.76934 ZT16-19 11.91925 11.91925 11.91925 ZT20-23 11.754950000000001 11.754950000000001 11.754950000000001