Year	Percent
1991	21.842
1992	22.353
1993	22.29
1994	23.36
1995	23.237
1996	22.14
1997	22.155
1998	22.221
1999	22.442
2000	22.563
2001	23.075
2002	23.297
2003	24.182
2004	24.493
2005	25.506
2006	26.654
2007	28.037
2008	28.736
2009	29.778
2010	29.493
2011	29.685
2012	28.976
2013	28.997
2014	29.573
2015	30.007
2016	30.115
2017	29.288
2018	29.423
2019	29.523
2020	29.605
2021	29.72
2022	29.846