Year	Number of
1990	359.65
1991	374.37
1992	391.02
1993	408.86
1994	426.67
1995	441.93
1996	454.57
1997	462.16
1998	468.51
1999	477.41
2000	484.34
2001	489.27
2002	494.09
2003	499.03
2004	507.19
2005	516
2006	522.1
2007	525.65
2008	528.88
2009	530.55
2010	532.01
2011	535
2012	544.3
2013	555.28
2014	566.73
2015	577.54
2016	590.66