Year	% of expense
1990	57.541060534960266
1991	60.609930142789125
1992	60.93475837476353
1993	62.46872401794883
1994	62.797518330513256
1995	52.202725673536634
1996	53.12915527238545
1997	51.56618890370068
1998	51.042121279058804
1999	52.01571313386234
2000	52.63664683403122
2001	51.13493379425972
2002	52.03981547096671
2003	50.109649343534954
2004	49.22656041822887
2005	51.136993472416876
2006	51.05533450542767
2007	50.614951840626546
2008	50.01294294536174
2009	50.74789196010792
2010	50.98549088957481
2011	50.214643771331055
2012	50.90539399984655
2013	51.667483225790754
2014	50.64204195821604
2015	49.72931169272877
2016	49.957546496262104
2017	48.7943228594481
2018	48.06741646790712
2019	49.05747619177825
2020	53.189049470750994
2021	52.144425371452996
2022	51.628348850465514