Year	Number of
1990	175.52
1991	174.26
1992	173.16
1993	171.93
1994	171.8
1995	172.84
1996	175.12
1997	178.51
1998	182.63
1999	181.85
2000	179.91
2001	179.38
2002	182.96
2003	185.08
2004	186.43
2005	188.31
2006	190.69
2007	193.07
2008	195.55
2009	196.69
2010	197.35
2011	199.42
2012	205.57
2013	207.92
2014	211.05
2015	214.9
2016	220.43