Year % of expense 1994 1.6045339123394546 1995 3.212596841494976 1996 4.049324746848636 1997 2.405165242728263 1998 2.0266584446078313 1999 1.8020219255675443 2000 2.893190280646665 2001 2.7144307503316654 2002 2.556315732902524 2003 2.478976055515605 2004 2.4042191323029183 2005 1.7987691147723361 2006 1.5948810797041721 2007 1.4680813830261925 2008 1.5907728273415789 2009 3.464710085059469 2010 4.222231892541141 2011 5.004710490749633 2012 5.172231650098869 2013 4.735795633441106 2014 4.541002799337841 2015 4.262201616981294 2016 3.6821776008959737 2017 3.3051486637089442 2018 2.576988499254203 2019 2.2910524543313 2020 1.9105025782549463 2021 1.3251491877849402 2022 1.3021311900408807