Year	Number of
1990	249.43
1991	255.45
1992	262.14
1993	269.37
1994	277.25
1995	285.9
1996	291.96
1997	298.81
1998	306.31
1999	314.5
2000	323.5
2001	330.46
2002	338.35
2003	347.05
2004	356.6
2005	367.1
2006	379.75
2007	393.35
2008	408.15
2009	424.05
2010	441.23
2011	460.15
2012	480.83
2013	502.97
2014	526.73
2015	552.12
2016	578.98