Year	Number of
1990	91.01
1991	94.77
1992	97.98
1993	102.04
1994	107.33
1995	113.09
1996	120.65
1997	127.52
1998	134.22
1999	140.88
2000	148.11
2001	151.02
2002	155.4
2003	158.71
2004	160.25
2005	160.23
2006	160.19
2007	159.12
2008	160.43
2009	162.34
2010	164.39
2011	166.2
2012	169.1
2013	172.66
2014	176.53
2015	180.4
2016	183.65