Year	Number of
1990	604.33
1991	593.8
1992	586.32
1993	584.62
1994	581.93
1995	575.21
1996	570.58
1997	576.47
1998	576.47
1999	587.87
2000	580.79
2001	572.02
2002	570.74
2003	566.81
2004	582.38
2005	569.07
2006	566.52
2007	567.74
2008	563.5
2009	560.43
2010	551.23
2011	554.71
2012	557.64
2013	568.29
2014	562.87
2015	575.89
2016	568.49