Year	Number of
1990	308.01
1991	321.4
1992	336.6
1993	341.61
1994	361.04
1995	365.43
1996	375.56
1997	374.08
1998	376.55
1999	389.99
2000	394.21
2001	403.56
2002	414
2003	415.17
2004	425.64
2005	432.17
2006	439.44
2007	446.58
2008	447.76
2009	450.36
2010	454.46
2011	454.7
2012	466.48
2013	462.61
2014	469.14
2015	470.76
2016	471.51