Year	Percent
1991	30.812
1992	31.245
1993	33.214
1994	34.334
1995	36.099
1996	37.147
1997	38.656
1998	37.989
1999	37.036
2000	36.642
2001	36.304
2002	35.702
2003	35.069
2004	37.194
2005	35.801
2006	36.882
2007	37.774
2008	38.285
2009	38.588
2010	39.486
2011	39.582
2012	39.396
2013	40.28
2014	40.155
2015	40.919
2016	41.789
2017	42.324
2018	43.213
2019	44.436
2020	45.256
2021	46.129
2022	46.785