Year	% of expense
1990	2.5809479117785137
1991	2.3249738766980146
1992	2.3882772020725493
1993	2.5602635125018725
1994	3.380381086803106
1995	1.7984208142839846
1996	1.898812951553247
1997	2.0154332043224894
1998	2.099465901491447
1999	2.2135594547007758
2000	2.427739053477659
2001	2.363663979465909
2002	2.253212435875582
2003	2.2041439360933954
2004	2.24230201596989
2005	2.189881911432484
2006	2.1721650229109324
2007	2.084635769790645
2008	1.9349380782047552
2009	1.7388271817201095
2010	1.2037975134528887
2011	1.6775213038933126
2012	1.8719656645553937
2013	1.9710538197760978
2014	2.4036362275989607
2015	2.5040222191643746
2016	2.7810331034732507
2017	2.93073047420388
2018	3.044592320428487
2019	3.2473919258821855
2020	2.978485892148664
2021	3.333102787424263
2022	3.9155783586977146