Year	Number of
1990	278.85
1991	282.09
1992	283.44
1993	283.44
1994	283.44
1995	284.47
1996	278.47
1997	274.04
1998	271.57
1999	271.29
2000	273.48
2001	273.94
2002	277.46
2003	282.58
2004	287.53
2005	291.79
2006	293.96
2007	294.65
2008	294.97
2009	295.34
2010	296.4
2011	300.5
2012	305.21
2013	310.13
2014	315.25
2015	320.53
2016	326.61