Year	Number of
1990	428.8
1991	442.8
1992	458.19
1993	474.47
1994	491.15
1995	508.31
1996	510.01
1997	511.6
1998	513.22
1999	515.34
2000	518.56
2001	514.66
2002	512.03
2003	510.31
2004	509.22
2005	508.96
2006	514.03
2007	519.43
2008	526.05
2009	533.32
2010	541.6
2011	553.1
2012	565.66
2013	578.55
2014	592.3
2015	606.98
2016	622.52