Year	Percent
1990	55.303
1991	55.149
1992	57.528
1993	60.053
1994	56.199
1995	51.213
1996	50.813
1997	50.852
1998	52.723
1999	51.413
2000	48.46
2001	48.419
2002	48.318
2003	46.878
2004	46.237
2005	46.878
2006	46.22
2007	45.733
2008	45.262
2009	43.548
2010	43.197
2011	42.119
2012	42.07
2013	41.954
2014	42.499
2015	43.118
2016	42.028
2017	41.805
2018	41.583
2019	41.361
2020	41.139
2021	40.916
2022	40.694
2023	40.472
2024	40.25
2025	40.027
2026	39.805
2027	39.583
2028	39.361
2029	39.138
2030	38.916