Year	Number of
1990	149.54
1991	146.9
1992	150.01
1993	154.19
1994	159.68
1995	166.98
1996	176.17
1997	183.17
1998	189.62
1999	192.99
2000	194.04
2001	192.43
2002	190.28
2003	187.56
2004	183.54
2005	178.78
2006	173.69
2007	171.81
2008	171.95
2009	169.59
2010	168.33
2011	167.69
2012	169.76
2013	170.37
2014	169.82
2015	169.73
2016	169.73