Year	Number of
1990	138.82
1991	144.14
1992	148.07
1993	152.95
1994	158.88
1995	161.8
1996	165.24
1997	174.34
1998	179.61
1999	180.12
2000	185.78
2001	189.39
2002	195.37
2003	203.84
2004	204.33
2005	212.77
2006	217.32
2007	231.29
2008	241.19
2009	250.61
2010	262.05
2011	276.58
2012	291.53
2013	305.75
2014	319.86
2015	333.57
2016	347.55