Year	Number of
1990	248.16
1991	248.75
1992	244.97
1993	248.01
1994	246.1
1995	247.44
1996	246.66
1997	249.24
1998	249.69
1999	248.76
2000	249.51
2001	255.34
2002	261.65
2003	264.53
2004	266.09
2005	272.35
2006	272.51
2007	281.61
2008	287.66
2009	294.65
2010	303.09
2011	309.43
2012	315.07
2013	321.9
2014	327.12
2015	327.62
2016	330.2