Volume hydrocarbon related Volume not hydrocarbon related 10 15 20 16 11 11 20 20 16 0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000 47,820 5,130 12,158 38,376 63,881 3,165 2009 2010 2011 2012 2013 2014 boatswain chairs that allowed workers to perform aerial work while suspended from a structure.