Year	Number of
1990	149.23
1991	155.43
1992	159.88
1993	164.49
1994	170.32
1995	182.4
1996	191.52
1997	199.1
1998	208.91
1999	215.33
2000	219.83
2001	218.96
2002	217.73
2003	217.64
2004	215.52
2005	209.19
2006	204.59
2007	200.78
2008	201.49
2009	204.72
2010	213.23
2011	218.84
2012	224.82
2013	231.3
2014	238.24
2015	245.67
2016	251.3