Year	Number of
1990	52.38
1991	53.74
1992	55.29
1993	56.98
1994	58.77
1995	60.64
1996	62.4
1997	64.25
1998	66.17
1999	68.28
2000	70.63
2001	72.86
2002	75.32
2003	78.01
2004	80.95
2005	84.19
2006	87.47
2007	90.98
2008	94.85
2009	99.02
2010	103.52
2011	106.92
2012	110.55
2013	114.3
2014	118.34
2015	122.69
2016	127.58