Year	%
1988	47.64881
1991	47.8351
1993	41.9852
1996	27.57893
1997	22.90768
1998	25.71345
1999	24.95452
2000	22.89215
2001	21.73605
2002	21.2689
2003	21.51282
2004	22.36412
2005	22.43198
2006	23.92315
2007	24.97198
2008	17.03477
2009	16.51451
2010	15.70925
2011	18.92049
2012	18.67751
2013	18.70887
2014	13.02769
2016	16.64028
2020	19.60706
2021	19.77056