Year	Number of
1990	158.83
1991	160.47
1992	162.32
1993	164.24
1994	166.04
1995	167.21
1996	167.55
1997	167.88
1998	166.35
1999	165.68
2000	163.97
2001	164.97
2002	160.8
2003	158.58
2004	157.06
2005	158.07
2006	157.07
2007	156.26
2008	156.33
2009	156.41
2010	155.82
2011	153.75
2012	154.07
2013	154.4
2014	154.52
2015	154.71
2016	155.36