condition mean min max ZT0-3 8.522414 8.522414 8.522414 ZT4-7 8.5136295 8.5136295 8.5136295 ZT8-11 7.80269 7.80269 7.80269 ZT12-15 7.671887 7.671887 7.671887 ZT16-19 7.3895995 7.3895995 7.3895995 ZT20-23 8.2830095 8.2830095 8.2830095