Year	Number of
1990	190.2
1991	192.5
1992	194.38
1993	194.56
1994	196.39
1995	200.6
1996	211.03
1997	223.9
1998	238.74
1999	253.58
2000	268.12
2001	279.73
2002	291.17
2003	304.84
2004	319.61
2005	336.24
2006	352.42
2007	369.61
2008	388.55
2009	408.65
2010	430.26
2011	445.25
2012	461.08
2013	477.51
2014	495.31
2015	514.79
2016	535.95