Year	Number of
1990	257.45
1991	271.95
1992	283.42
1993	295.82
1994	304.4
1995	302.92
1996	309.04
1997	310.85
1998	314.58
1999	323.04
2000	332.08
2001	341.62
2002	346.62
2003	356.53
2004	368.48
2005	372.62
2006	381.53
2007	394.81
2008	403.72
2009	412.39
2010	420.01
2011	435.87
2012	450.74
2013	472.82
2014	494.1
2015	514.96
2016	538.67