Year	Number of
1990	32.26
1991	33.18
1992	34.12
1993	35.05
1994	36.05
1995	37.34
1996	38.56
1997	40
1998	41.72
1999	43.8
2000	45.72
2001	48
2002	50.19
2003	52.24
2004	55.11
2005	57.39
2006	59.59
2007	61.89
2008	64.15
2009	66.78
2010	69.48
2011	72.05
2012	74.66
2013	77.53
2014	80.35
2015	83.55
2016	87.34