Year	Number of
1990	38.27
1991	39.16
1992	39.95
1993	40.84
1994	41.9
1995	42.38
1996	43.18
1997	45.22
1998	46.14
1999	46.86
2000	46.51
2001	47.33
2002	49.44
2003	54.15
2004	54.84
2005	56.66
2006	57.7
2007	60.25
2008	61.3
2009	64.53
2010	67.07
2011	69.83
2012	72.22
2013	72.67
2014	75.91
2015	75.72
2016	76.46