Year	Number of
1990	54.27
1991	58.14
1992	63.01
1993	68.5
1994	74.99
1995	80.75
1996	84.77
1997	88.45
1998	92.44
1999	96.74
2000	98.91
2001	101.2
2002	104.72
2003	105.95
2004	107.97
2005	110.22
2006	114.37
2007	118.89
2008	122.95
2009	128.53
2010	134.55
2011	138.88
2012	144.14
2013	149.14
2014	154.87
2015	160.85
2016	167.46