Year	Number of
1990	34.05
1991	35.99
1992	38.02
1993	40.14
1994	42.34
1995	44.67
1996	46.04
1997	47.52
1998	49.12
1999	50.92
2000	52.98
2001	54.06
2002	55.38
2003	56.85
2004	58.42
2005	60.12
2006	61.92
2007	63.79
2008	65.84
2009	68.04
2010	70.45
2011	72.66
2012	75.06
2013	77.57
2014	80.28
2015	83.2
2016	86.14