Year	Percent
1990	33.84
1991	34.02
1992	34.59
1993	35.1
1994	36.278
1995	36.685
1996	37.214
1997	37.993
1998	38.376
1999	39.079
2000	40.582
2001	39.461
2002	41.914
2003	43.365
2004	44.725
2005	46.099
2006	47.449
2007	48.353
2008	49.669
2009	50.777
2010	51.544
2011	52.126
2012	52.644
2013	52.619
2014	52.376
2015	52.316
2016	52.302
2017	52.152
2018	51.967
2019	51.742
2020	51.476
2021	51.207
2022	50.91
2023	50.599
2024	50.292
2025	49.999
2026	49.758
2027	49.548
2028	49.358
2029	49.167
2030	48.956