Year	Percent
1989	21.01222
1990	17.94474
1991	12.98534
1992	48.2546
1993	30.49385
1994	23.19533
1995	25.89429
1996	21.84979
1997	22.52721
1998	24.55126
1999	26.17349
2000	24.03362
2001	24.21732
2002	24.45834
2003	23.87829
2004	22.16396
2005	21.51018
2006	21.00293
2007	21.54207
2008	22.07293
2009	20.49697
2010	21.13996
2011	19.92418
2012	20.22611
2013	20.40039
2014	20.64592
2015	20.57079
2016	20.5264
2017	20.68849