Year	Number of
1990	0.72
1991	0.73
1992	0.75
1993	0.77
1994	0.78
1995	0.8
1996	0.83
1997	0.85
1998	0.88
1999	0.89
2000	0.91
2001	0.92
2002	0.94
2003	0.95
2004	0.97
2005	0.99
2006	1
2007	1.01
2008	1.02
2009	1.05
2010	1.06
2011	1.08
2012	1.12
2013	1.14
2014	1.16
2015	1.19
2016	1.22