Year	Number of
1990	280.16
1991	273.39
1992	270.09
1993	258.59
1994	254.21
1995	241.19
1996	234.31
1997	230.4
1998	229.03
1999	231.77
2000	234.03
2001	237.5
2002	240.13
2003	241.05
2004	241.12
2005	239.7
2006	235.02
2007	236.62
2008	243.21
2009	234.66
2010	227.24
2011	221.84
2012	218.89
2013	216.91
2014	219.39
2015	223.52
2016	230.34