Year	Number of
1990	323.35
1991	330.02
1992	337.13
1993	344.23
1994	351.04
1995	357.57
1996	354.53
1997	350.96
1998	347.49
1999	344.78
2000	343.43
2001	339.61
2002	338.12
2003	338.44
2004	339.78
2005	341.9
2006	347.91
2007	354.32
2008	361.38
2009	368.94
2010	377.16
2011	391.25
2012	406.48
2013	422.61
2014	440.04
2015	458.95
2016	478.82