Year	Number of
1990	56.01
1991	58
1992	54.35
1993	54.61
1994	59.08
1995	68.08
1996	82.24
1997	84.12
1998	83.8
1999	86.13
2000	91.33
2001	97.75
2002	106.06
2003	113.22
2004	118.44
2005	126.52
2006	134.13
2007	138.47
2008	141.69
2009	145.27
2010	151.57
2011	143.16
2012	148.48
2013	150.56
2014	158.75
2015	162.59
2016	162.54