Year	Number of
1990	129.72
1991	133.7
1992	137.47
1993	140.13
1994	143.15
1995	147.84
1996	152.98
1997	158.19
1998	161.08
1999	159.63
2000	153.8
2001	156.5
2002	155.74
2003	161.14
2004	158.64
2005	156.81
2006	155.79
2007	154.49
2008	157.25
2009	159.16
2010	163.83
2011	167.93
2012	170.57
2013	166.93
2014	174.38
2015	171.55
2016	169.52