Year	%
1988	2.26
1993	2.11
1995	33.21
1996	27.08
1997	29.26
1998	35.14
1999	26.65
2000	36.47
2001	29.64
2002	31.2
2003	29.59
2004	30.55
2005	32.89
2006	31.04
2007	32.1
2008	26.13
2009	26.05
2010	30.09
2011	30.76
2012	30.32
2013	29
2014	26.36
2015	27.35
2016	24.96
2017	24.32
2018	23.64
2019	22.1
2020	21.17
2021	21.99