Year	Percent
1990	32.075
1991	31.854
1992	33.848
1993	35.484
1994	35.49
1995	34.357
1996	34.692
1997	35.546
1998	36.321
1999	36.525
2000	35.55
2001	35.444
2002	35.474
2003	36.557
2004	38.879
2005	38.342
2006	39.268
2007	41.444
2008	43.105
2009	43.379
2010	47.059
2011	48.945
2012	49.155
2013	49.567
2014	50.13
2015	50.108
2016	50.351
2017	50.582
2018	50.794
2019	50.986
2020	51.157
2021	51.319
2022	51.463
2023	51.591
2024	51.709
2025	51.817
2026	51.934
2027	52.045
2028	52.151
2029	52.248
2030	52.334