Year	Percent
1990	33.989
1991	31.962
1992	31.399
1993	32.398
1994	33.129
1995	34.008
1996	33.702
1997	33.659
1998	33.534
1999	34.759
2000	44.709
2001	43.082
2002	37.781
2003	34.962
2004	32.245
2005	29.643
2006	27.166
2007	29.76
2008	26.099
2009	25.93
2010	28.306
2011	30.81
2012	36.67
2013	34.18
2014	29
2015	29.6
2016	29.949
2017	29.695
2018	29.441
2019	29.186
2020	28.932
2021	28.678
2022	28.424
2023	28.169
2024	27.915
2025	27.661
2026	27.407
2027	27.152
2028	26.898
2029	26.644
2030	26.39