Year	Number of
1990	47.11
1991	47.06
1992	46.73
1993	46.24
1994	45.76
1995	45.41
1996	46.21
1997	47.24
1998	48.68
1999	50.34
2000	52.2
2001	54.39
2002	56.79
2003	59.42
2004	62.08
2005	64.71
2006	67.07
2007	69.32
2008	71.54
2009	73.79
2010	76.14
2011	78.49
2012	80.98
2013	83.65
2014	86.44
2015	89.34
2016	92.68