Year	Number of
1990	225.85
1991	236.78
1992	248.24
1993	262.39
1994	278.22
1995	295.17
1996	311.91
1997	330.5
1998	355.12
1999	380.36
2000	396.25
2001	413.54
2002	427.03
2003	440.85
2004	452.31
2005	460.35
2006	472.11
2007	484.64
2008	497.95
2009	507.7
2010	514.41
2011	520.6
2012	525.21
2013	524.51
2014	526.8
2015	532.2
2016	542.77