Year	Number of
1990	228.79
1991	235.22
1992	241.26
1993	246.69
1994	252.17
1995	259.13
1996	264.27
1997	270.34
1998	277.29
1999	284.73
2000	291.51
2001	302.71
2002	315.45
2003	325.91
2004	338.06
2005	351.54
2006	363.46
2007	375.08
2008	385.39
2009	394.94
2010	404.11
2011	412.18
2012	418.58
2013	424.61
2014	431.83
2015	438.13
2016	444.28