Year	Number of
1990	297.69
1991	304.68
1992	304.85
1993	307.66
1994	310.33
1995	315.16
1996	320.57
1997	329.14
1998	338.96
1999	353.31
2000	369.23
2001	380.6
2002	391.31
2003	406.21
2004	435.38
2005	451.94
2006	462.76
2007	468.43
2008	476.09
2009	482.07
2010	488.57
2011	490.51
2012	495.15
2013	490.96
2014	492.29
2015	487.14
2016	496.87