Year	Number of
1990	238.41
1991	245.35
1992	252.62
1993	259.37
1994	267
1995	275.78
1996	269.96
1997	264.03
1998	258.21
1999	252.05
2000	245.78
2001	254.76
2002	264.22
2003	275.67
2004	287.75
2005	300.83
2006	318.15
2007	336.08
2008	355.21
2009	376.27
2010	400.11
2011	412.49
2012	426.36
2013	440.14
2014	454.6
2015	469.95
2016	487.08