Year	Number of
1990	49.89
1991	51.08
1992	52.97
1993	54.65
1994	57.58
1995	59.12
1996	60.12
1997	62.76
1998	67.51
1999	73.2
2000	77.53
2001	81.18
2002	84.69
2003	88.68
2004	91.46
2005	92.4
2006	89.07
2007	87.36
2008	88.01
2009	89.07
2010	90.27
2011	89.75
2012	90.34
2013	92.34
2014	94.14
2015	95.63
2016	97.58