Year	Number of
1990	262.42
1991	266
1992	271.4
1993	275.84
1994	280.82
1995	288.62
1996	287.09
1997	290.94
1998	294.44
1999	298.09
2000	299.79
2001	311.13
2002	324.92
2003	338.52
2004	353.11
2005	370.41
2006	378.6
2007	387.87
2008	400.27
2009	412.52
2010	426.01
2011	442.12
2012	459.73
2013	477.75
2014	497.91
2015	517.82
2016	537.08