Year	Number of
1990	42.3
1991	43.94
1992	44.08
1993	43.7
1994	46.01
1995	49.23
1996	56.07
1997	58.33
1998	64.46
1999	68.48
2000	75.02
2001	77.85
2002	78.62
2003	79.73
2004	79.71
2005	79.87
2006	81.11
2007	82.31
2008	84.11
2009	85.81
2010	87.23
2011	87.54
2012	87.92
2013	88.38
2014	88.42
2015	87.29
2016	87.31