Year	Number of
1990	113.69
1991	129.8
1992	147.05
1993	168.63
1994	190.63
1995	213.19
1996	221.28
1997	230.11
1998	232.17
1999	234.59
2000	237.57
2001	241.96
2002	246.44
2003	252.12
2004	258.56
2005	266.1
2006	271.18
2007	276.74
2008	283.69
2009	291.41
2010	300.12
2011	312.69
2012	326.2
2013	339.7
2014	354.92
2015	372
2016	393.55