Year	Percent
1990	29.972
1991	30.186
1992	30.554
1993	30.922
1994	31.441
1995	31.923
1996	32.22
1997	32.633
1998	33.172
1999	33.798
2000	34.431
2001	34.743
2002	35.262
2003	35.976
2004	36.836
2005	37.757
2006	39.127
2007	40.659
2008	42.319
2009	43.079
2010	43.424
2011	43.194
2012	43.085
2013	42.93
2014	42.692
2015	42.436
2016	41.92
2017	41.606
2018	41.345
2019	41.121
2020	40.908
2021	40.459
2022	40.055
2023	39.721
2024	39.47
2025	39.298
2026	38.974
2027	38.743
2028	38.61
2029	38.564
2030	38.582