Year	Number of
1990	54.88
1991	50.06
1992	46.84
1993	47.1
1994	46.61
1995	49.91
1996	51.19
1997	52.62
1998	52.26
1999	51.84
2000	52.83
2001	51.91
2002	52.67
2003	55.74
2004	59.21
2005	62.05
2006	65.2
2007	66.67
2008	67.44
2009	67.51
2010	69.6
2011	70.37
2012	74.46
2013	77.01
2014	81.2
2015	84.73
2016	90.84