Year	Number of
1990	74.01
1991	78.53
1992	84.26
1993	90.55
1994	98.56
1995	107.3
1996	115.03
1997	122.8
1998	130.7
1999	138.17
2000	146.31
2001	146.19
2002	145.97
2003	143.2
2004	140.59
2005	137.61
2006	138.91
2007	140.29
2008	143.62
2009	145.67
2010	148.28
2011	149.57
2012	152.33
2013	155.39
2014	156.93
2015	160
2016	163.33