Year	Number of
1990	530.4
1991	534.3
1992	537.49
1993	542.12
1994	544.82
1995	552.48
1996	562.59
1997	581.75
1998	590.92
1999	591.79
2000	588.75
2001	595.58
2002	601.37
2003	601.83
2004	591.58
2005	589.16
2006	589.49
2007	587.44
2008	584.2
2009	567.04
2010	567.61
2011	571.48
2012	570.98
2013	581.35
2014	578.95
2015	573.67
2016	568.57