Year	Number of
1990	127.31
1991	133.02
1992	140.3
1993	148.46
1994	156.39
1995	163.14
1996	167.92
1997	169.72
1998	176.58
1999	173.1
2000	173.2
2001	171.83
2002	182.39
2003	189.27
2004	189.53
2005	200.23
2006	209.05
2007	219.07
2008	236.11
2009	245.46
2010	255.62
2011	272.9
2012	292.13
2013	315.22
2014	343.63
2015	371.22
2016	401.1