Year	% of expense
1990	26.071270892462945
1991	23.237672127005517
1992	25.43586123041321
1993	25.352557079626624
1994	27.02428070973289
1995	22.058144634489764
1996	25.500784471120518
1997	27.179431675062972
1998	24.777602758583335
1999	26.47159086066866
2000	24.626963758240695
2001	28.13882780494646
2002	32.15430977861917
2003	33.52768741860976
2004	27.660979687601028
2005	24.256757165957087
2006	24.261582328179912
2007	25.46399613051969
2008	25.07461312695384
2009	30.558091022211347
2010	32.62640974486718
2011	30.58208584330897
2012	30.157691910168765
2013	31.558122179181918
2014	28.51418415722522
2015	25.785756143961468
2016	30.444018784594824
2017	33.34835583471049
2018	36.31731740828392
2019	35.55258394126681
2020	32.856227105604866
2021	34.078610815267304
2022	41.317163257160594