Year	Percent
1991	22.304
1992	22.156
1993	22.142
1994	22.38
1995	22.905
1996	23.231
1997	23.474
1998	23.409
1999	23.524
2000	23.482
2001	23.37
2002	23.102
2003	23.505
2004	24.134
2005	24.881
2006	25.408
2007	25.889
2008	26.295
2009	26.824
2010	27.895
2011	29.44
2012	29.911
2013	30.213
2014	30.545
2015	30.611
2016	31.41
2017	31.874
2018	32.368
2019	32.946
2020	33.615
2021	34.264
2022	34.843