Year	Number of
1990	74.18
1991	75.69
1992	76.19
1993	77.26
1994	76.4
1995	74.77
1996	73.81
1997	73.68
1998	75.67
1999	79.5
2000	84.32
2001	90.65
2002	96.5
2003	102.51
2004	108.63
2005	114.22
2006	117.68
2007	121.1
2008	124.14
2009	128.69
2010	131.07
2011	132.68
2012	135.19
2013	138.27
2014	141.88
2015	145.87
2016	149.43