condition mean min max ZT0-3 4.73079141075 3.685382188 5.7762006335 ZT4-7 9.7457856895 8.166829669 11.32474171 ZT8-11 7.14451089675 6.2877349670000005 8.0012868265 ZT12-15 5.59962955675 4.254505061 6.9447540525 ZT16-19 8.59059187875 7.4677685085 9.713415249 ZT20-23 14.042855475 13.57482191 14.51088904