Year	% of expense
1997	7.707354100370771
1998	7.664173448878052
1999	8.888142613270645
2000	10.345943846170446
2001	14.885145482388973
2003	20.48728813559322
2004	14.989577845477243
2005	13.999583291813497
2006	15.620267010714088
2007	15.213323785544338
2008	14.275186300320481
2009	15.089981338170618
2010	13.756075056276298
2011	12.957645369705673
2012	13.421985031091626
2013	11.951078107267971
2014	10.97395141209408
2015	11.396722762655275
2016	12.188054782118716
2017	13.046896997632729
2018	12.90863609019121
2019	11.446972427561757
2020	11.11748631371505
2021	11.10821518650444
2022	10.495459819658185