Year	Number of
1990	274.72
1991	272.7
1992	269.37
1993	264.18
1994	259.9
1995	257.29
1996	262.65
1997	268.37
1998	274.33
1999	279.62
2000	284.17
2001	305.89
2002	329.26
2003	357.72
2004	386.78
2005	416.34
2006	434.11
2007	450.98
2008	468.41
2009	487.86
2010	510.06
2011	519.41
2012	530.25
2013	538.01
2014	545.17
2015	552.12
2016	566.58