Year	% of expense
1990	1.5884898449098201
1991	1.2775581852106452
1992	1.5255356386000019
1993	2.099373369263014
1994	1.8986355643599617
1995	4.223322991773102
1996	4.60644328047643
1997	5.069592648957552
1998	5.022433942100094
1999	5.0512594918147276
2000	5.062513313779147
2001	4.916110589097164
2002	4.715096903050501
2003	4.299620097303141
2004	4.105946885862144
2005	4.023262620459398
2006	3.901651896084752
2007	4.632580982069538
2008	4.510463005747178
2009	3.9955254545152483
2010	3.7750194982578944
2011	3.3614669148315115
2012	3.2570094874359676
2013	3.362689450817867
2014	3.42821186660251
2015	3.517171206962705
2016	3.7358491965297698
2017	3.7727203863620407
2018	3.748955407822051
2019	3.7715047745594337
2020	3.524381726007428
2021	3.549629717162786
2022	3.655074866038578