Year	Percent
1991	62.159
1992	61.3
1993	59.911
1994	58.617
1995	57.84
1996	56.849
1997	56.431
1998	56.242
1999	55.672
2000	54.418
2001	53.387
2002	51.714
2003	49.68
2004	47.774
2005	46.259
2006	45.074
2007	44.127
2008	43.304
2009	42.41
2010	41.353
2011	40.119
2012	38.843
2013	37.541
2014	36.237
2015	34.961
2016	33.964
2017	33.725
2018	33.51
2019	33.307
2020	33.098
2021	32.902
2022	32.725