condition mean min max ZT0-3 8.920071 8.920071 8.920071 ZT4-7 8.912798 8.912798 8.912798 ZT8-11 9.2941665 9.2941665 9.2941665 ZT12-15 9.382887 9.382887 9.382887 ZT16-19 8.5943905 8.5943905 8.5943905 ZT20-23 8.6118265 8.6118265 8.6118265