Year	Number of
1990	233.23
1991	251.44
1992	271.73
1993	294.29
1994	319.25
1995	347
1996	363.11
1997	380.31
1998	398.54
1999	417.63
2000	437.58
2001	441.91
2002	446.19
2003	450.65
2004	455.32
2005	460.44
2006	465.15
2007	470.61
2008	477.11
2009	484.38
2010	492.49
2011	504.21
2012	517.45
2013	531.88
2014	547.32
2015	563.61
2016	580.9