Year	Number of
1990	44.34
1991	44.52
1992	44.45
1993	44.06
1994	45.13
1995	46.33
1996	47.74
1997	49.45
1998	50
1999	51.71
2000	52.6
2001	54.03
2002	56.26
2003	57.74
2004	60.05
2005	62.59
2006	64.36
2007	64.92
2008	65.35
2009	65.93
2010	65.29
2011	64.3
2012	63.82
2013	63.68
2014	63.67
2015	63.7
2016	63.58