Year	Number of
1990	110.68
1991	111.74
1992	110.73
1993	107.16
1994	104.92
1995	106.72
1996	106.79
1997	109.41
1998	117.54
1999	129.55
2000	148.89
2001	161.04
2002	176.37
2003	181.74
2004	188.18
2005	194.76
2006	193.33
2007	190.75
2008	187.34
2009	185.49
2010	183.09
2011	177.88
2012	176.23
2013	175.66
2014	174.23
2015	172.42
2016	172.66