Year	Number of
1990	175.26
1991	175.19
1992	182.38
1993	190.57
1994	193.22
1995	197.47
1996	203.93
1997	209.64
1998	217.09
1999	217.49
2000	215.75
2001	215.28
2002	217.24
2003	222.57
2004	225.21
2005	227.43
2006	229.82
2007	236.46
2008	244.71
2009	250.96
2010	260.16
2011	265.23
2012	269.61
2013	274.53
2014	281.47
2015	290.04
2016	297.93