Year	Percent
1991	22.516
1992	22.714
1993	22.992
1994	23.346
1995	23.774
1996	24.233
1997	24.623
1998	25.052
1999	25.476
2000	25.875
2001	26.112
2002	26.32
2003	26.276
2004	26.143
2005	26.075
2006	26.31
2007	26.937
2008	27.234
2009	27.343
2010	28.752
2011	28.977
2012	29.199
2013	29.198
2014	29.627
2015	30.064
2016	30.524
2017	30.711
2018	30.891
2019	31.065
2020	31.229
2021	31.374
2022	31.512