Year	Number of
1990	46.08
1991	45.43
1992	44.55
1993	43.38
1994	44.1
1995	45.01
1996	47.4
1997	49.34
1998	51.37
1999	54.14
2000	57.67
2001	58.54
2002	61.21
2003	61.75
2004	63.58
2005	65.64
2006	67.96
2007	71.69
2008	74.91
2009	78.15
2010	81.24
2011	83.29
2012	84.71
2013	86.25
2014	88.03
2015	89.86
2016	91.89