Year	Number of
1990	358.39
1991	364.67
1992	383.14
1993	398.12
1994	434.69
1995	497.64
1996	488.04
1997	488.89
1998	482.41
1999	473.29
2000	479.31
2001	473.29
2002	468.61
2003	455.31
2004	451.72
2005	446.02
2006	446.22
2007	441.79
2008	436.12
2009	431.28
2010	437.77
2011	440.93
2012	444.87
2013	451.25
2014	459.08
2015	468.69
2016	481.25