Year	Number of
1990	228.85
1991	228.41
1992	221.72
1993	211.67
1994	203.51
1995	197.6
1996	222.54
1997	251.33
1998	294.64
1999	331.09
2000	362.26
2001	376.66
2002	395.97
2003	405.4
2004	419.57
2005	436.22
2006	460.01
2007	480.52
2008	494.67
2009	507.38
2010	517.3
2011	525.03
2012	535.12
2013	555.42
2014	579.86
2015	609.05
2016	637.47