Year	Number of
1990	133.31
1991	139.14
1992	145.2
1993	153.52
1994	159.78
1995	165.14
1996	170.56
1997	174.21
1998	177.87
1999	178.11
2000	185.53
2001	192.81
2002	200.11
2003	209.14
2004	212.92
2005	219.27
2006	230.05
2007	237.39
2008	248.83
2009	259.3
2010	268.65
2011	277.79
2012	285.29
2013	297.77
2014	310.43
2015	324.21
2016	339.44