Year	Number of
1990	148.85
1991	150.07
1992	152.18
1993	156.08
1994	160.63
1995	164.22
1996	162.74
1997	162.62
1998	171.3
1999	171.97
2000	174.71
2001	180.47
2002	186.71
2003	197.91
2004	206.97
2005	215.56
2006	225.15
2007	233.83
2008	245.27
2009	256.02
2010	266.53
2011	279.35
2012	293.46
2013	308.68
2014	325.26
2015	343.09
2016	360.17