Year	Number of
1990	110.9
1991	136.3
1992	163.3
1993	181.19
1994	195.69
1995	213.09
1996	222.55
1997	236.95
1998	245.48
1999	250.97
2000	257.24
2001	261.7
2002	267.38
2003	274.44
2004	283.35
2005	286.36
2006	290.95
2007	293.03
2008	300.75
2009	303.04
2010	307.95
2011	312.07
2012	318.69
2013	321.37
2014	319.01
2015	321.04
2016	324.28