Year	Number of
1990	135.06
1991	139.8
1992	145.5
1993	146.96
1994	153.54
1995	153.52
1996	153.05
1997	159.58
1998	160.44
1999	171.39
2000	181.15
2001	191.44
2002	201.39
2003	201.32
2004	208.75
2005	208.65
2006	217.15
2007	218.66
2008	216.92
2009	216.52
2010	222.24
2011	222.61
2012	233.82
2013	233.92
2014	239.42
2015	241.47
2016	243.22