Year	Number of
1990	528.54
1991	512.62
1992	495.11
1993	489.85
1994	489.98
1995	488.3
1996	477.15
1997	473.05
1998	469.71
1999	472.51
2000	465.73
2001	471.12
2002	469.4
2003	476.14
2004	490.14
2005	500.04
2006	510.95
2007	510.21
2008	507.97
2009	505.38
2010	496.95
2011	496.93
2012	494.42
2013	495.82
2014	510.54
2015	522.24
2016	530.98