Year	Percent
1990	46.202
1991	49.294
1992	51.383
1993	50.958
1994	49.945
1995	48.2
1996	44.9
1997	41.78
1998	43.53
1999	45.01
2000	43.55
2001	42.53
2002	28.21
2003	23.25
2004	18.54
2005	16.79
2006	16.61
2007	19.46
2008	17.87
2009	16.25
2010	14.59
2011	13.7
2012	13.68
2013	12.95
2014	12.52
2015	10.57
2016	9.98
2017	9.681
2018	9.382
2019	9.082
2020	8.783
2021	8.484
2022	8.185
2023	7.886
2024	7.587
2025	7.287
2026	6.988
2027	6.689
2028	6.39
2029	6.091
2030	5.791