Year	Number of
1990	57.13
1991	57.2
1992	58.59
1993	60.13
1994	59.93
1995	61.25
1996	62.08
1997	60.69
1998	60.55
1999	59.67
2000	58.55
2001	59.85
2002	56.31
2003	54.23
2004	53.68
2005	54.73
2006	56.52
2007	58.03
2008	59.74
2009	61.44
2010	64.74
2011	67.14
2012	68.25
2013	70.01
2014	73.35
2015	74.52
2016	76.15