Year	Number of
1990	59.52
1991	60.41
1992	61.51
1993	62.53
1994	63.7
1995	65.04
1996	68.02
1997	71.25
1998	74.9
1999	78.6
2000	82.38
2001	84.82
2002	87.44
2003	90.97
2004	94.65
2005	98.42
2006	99.81
2007	101
2008	101.41
2009	101.96
2010	103.05
2011	105.48
2012	108.54
2013	110.73
2014	112.57
2015	113.85
2016	115.57