Year	Number of
1990	1.95
1991	1.96
1992	1.99
1993	2.01
1994	2.05
1995	2.09
1996	1.99
1997	1.89
1998	1.8
1999	1.74
2000	1.69
2001	1.67
2002	1.65
2003	1.63
2004	1.62
2005	1.6
2006	1.62
2007	1.64
2008	1.66
2009	1.68
2010	1.7
2011	1.76
2012	1.83
2013	1.9
2014	1.97
2015	2.04
2016	2.19