Year	Number of
1990	114.41
1991	121.39
1992	128.81
1993	136.31
1994	144.31
1995	152.97
1996	164.71
1997	177.4
1998	191.16
1999	205.97
2000	222.05
2001	239.6
2002	258.11
2003	278.06
2004	299.71
2005	323.61
2006	339.88
2007	357.28
2008	375.69
2009	395.18
2010	416.31
2011	429.41
2012	442.57
2013	455.92
2014	469.46
2015	483.19
2016	497.37