Year % of expense 2005 27.943567536917108 2006 28.783034843847105 2007 27.539706536646957 2008 27.583293408664396 2009 28.23368220819958 2010 28.216991916993354 2011 29.25608065018262 2012 28.654029519277618 2013 28.77520334742873 2014 26.258552323688704 2015 27.39732493795665 2016 27.244482199586518 2017 26.792729437671692 2018 25.5375843607538 2019 26.966980225781157 2020 25.839304994636798 2021 25.939147948207648 2022 25.980104207193396