Year	Number of
1990	0.82
1991	0.83
1992	0.83
1993	0.85
1994	0.85
1995	0.87
1996	0.87
1997	0.87
1998	0.89
1999	0.91
2000	0.92
2001	0.92
2002	0.94
2003	0.96
2004	0.99
2005	1.01
2006	1.04
2007	1.06
2008	1.07
2009	1.08
2010	1.11
2011	1.13
2012	1.15
2013	1.17
2014	1.2
2015	1.22
2016	1.24