condition mean min max ZT0-3 7.671887 7.671887 7.671887 ZT4-7 8.1793185 8.1793185 8.1793185 ZT8-11 7.4553625 7.4553625 7.4553625 ZT12-15 7.609211999999999 7.609211999999999 7.609211999999999 ZT16-19 9.590174000000001 9.590174000000001 9.590174000000001 ZT20-23 10.1462725 10.1462725 10.1462725