A slump in sales of manufactured coal and petroleum products in June dragged down Canada\'s overall manufacturing numbers, Statistics Canada said Thursday. While 12 of 21 industry groups responsible for 60 percent of manufacturing reported increases in sales in June, the national figure was down 0.4 percent on a monthly basis to $48.9 billion, the agency said. \"Sales of petroleum and coal products fell 10.6 percent in June,\" StatsCan said. \"A number of factors contributed to the decline, including a 4.9 percent drop in prices, ongoing shutdowns at a number of refineries as well as lower volumes at other refineries.\" Sales in that industry are now at their lowest level since August 2010. Had that industry been excluded, manufacturing sales in the other sectors increased 1.1 percent, the report said. The highest gainer was machinery manufacturers, who reported a 5.2 percent increase in sales, followed by transportation equipment sales, which were up 1.7 percent in June, the agency said.