condition mean min max ZT0-3 7.180113 7.180113 7.180113 ZT4-7 8.137988 8.137988 8.137988 ZT8-11 7.789823 7.789823 7.789823 ZT12-15 7.671887 7.671887 7.671887 ZT16-19 7.832858 7.832858 7.832858 ZT20-23 7.4313395 7.4313395 7.4313395