Year	Number of
1990	569.63
1991	567.68
1992	564.94
1993	561.93
1994	560.22
1995	560.73
1996	558.18
1997	556.3
1998	555.27
1999	553.78
2000	552.84
2001	555.23
2002	556.56
2003	558.5
2004	561.92
2005	566.18
2006	562.76
2007	559.25
2008	556.38
2009	554.44
2010	552.99
2011	556.17
2012	559.82
2013	559.27
2014	559.74
2015	561.87
2016	564.42