Year	Number of
1990	181.88
1991	187.82
1992	197.39
1993	205.16
1994	213.37
1995	222.23
1996	230.95
1997	245.89
1998	253.61
1999	269.4
2000	280.59
2001	297.83
2002	319.16
2003	344.53
2004	362.42
2005	374.32
2006	399.05
2007	427.25
2008	449.74
2009	477.82
2010	503.5
2011	529.44
2012	558.66
2013	581.06
2014	607.1
2015	629.3
2016	634.45