Year	Number of
1990	46.18
1991	45.98
1992	45.85
1993	45.56
1994	45.24
1995	45.17
1996	44.49
1997	43.97
1998	44.14
1999	45.12
2000	46.08
2001	45.84
2002	47.12
2003	47.91
2004	49.64
2005	49.52
2006	51.27
2007	52.97
2008	54.04
2009	55.94
2010	56.77
2011	56.83
2012	58.42
2013	59.76
2014	60.92
2015	62.23
2016	63.71