Year	Number of
1990	56.94
1991	59.14
1992	60.01
1993	61.48
1994	61.6
1995	62.2
1996	63.18
1997	63.89
1998	61.95
1999	64.59
2000	65.28
2001	65.85
2002	67.52
2003	69.2
2004	66.95
2005	67.49
2006	68.24
2007	69.83
2008	72.25
2009	71.67
2010	73.66
2011	74.68
2012	76.03
2013	77.38
2014	78.87
2015	80.41
2016	82.2