Year	Number of
1990	321.29
1991	322.33
1992	323.31
1993	324.27
1994	325.55
1995	327.74
1996	327.15
1997	326.58
1998	326.2
1999	325.94
2000	325.92
2001	329.41
2002	333.46
2003	338.18
2004	343.92
2005	350.55
2006	356.44
2007	362.77
2008	369.87
2009	377.4
2010	385.49
2011	397.28
2012	409.77
2013	423.17
2014	437.68
2015	452.32
2016	467.62