Year	Number of
1990	147.85
1991	152.25
1992	156.68
1993	161.5
1994	165.91
1995	172.08
1996	177.82
1997	182.81
1998	185.42
1999	187.84
2000	192.41
2001	194.31
2002	200.21
2003	206.71
2004	212.57
2005	218.38
2006	223.62
2007	227.66
2008	253.29
2009	234.42
2010	242.72
2011	246.01
2012	252.99
2013	260.09
2014	267.86
2015	275.72
2016	283.91