Year	Number of
1990	84.16
1991	86.18
1992	87.68
1993	91.44
1994	94.73
1995	97.95
1996	100.64
1997	102.91
1998	104.59
1999	105.68
2000	106.96
2001	108.16
2002	109.19
2003	108.55
2004	111.06
2005	113.81
2006	119.48
2007	126.29
2008	131.98
2009	138.89
2010	143.86
2011	141.08
2012	139.53
2013	137.9
2014	136.86
2015	137.26
2016	137.75