Year	Number of
1990	567.39
1991	575.76
1992	573.15
1993	575.95
1994	570.1
1995	569.5
1996	561.12
1997	569.08
1998	568.28
1999	568.85
2000	561.51
2001	566.51
2002	564.22
2003	570.5
2004	578.03
2005	591.14
2006	596.85
2007	614.8
2008	608.58
2009	617.45
2010	610.91
2011	613.15
2012	611.74
2013	612.75
2014	606.38
2015	603.69
2016	602.89