Year	%
1988	37.49956
1990	32.1802
1991	30.25235
1993	48.03318
1996	23.71206
1997	40.47403
1999	36.71201
2000	30.00992
2001	33.58805
2002	26.90885
2003	27.44199
2004	24.51838
2005	22.46039
2006	20.16369
2007	18.98133
2008	26.1783
2009	18.19753
2010	17.63599
2011	23.78704
2012	19.09642
2013	23.4326
2014	23.2579
2015	22.93954
2016	23.4536
2017	24.13237
2018	18.07533
2019	18.39377
2020	19.76141
2021	20.47506