Year	Percent
1991	23.668
1992	25.3
1993	25.049
1994	27.754
1995	29.356
1996	28.136
1997	29.139
1998	29.701
1999	29.07
2000	29.618
2001	30.747
2002	31.01
2003	31.822
2004	32.376
2005	32.546
2006	33.186
2007	33.714
2008	34.172
2009	34.559
2010	35.954
2011	36.768
2012	37.463
2013	38.682
2014	37.172
2015	37.388
2016	36.276
2017	36.516
2018	36.682
2019	36.824
2020	36.963
2021	37.092
2022	37.199