Year	Number of
1990	98.21
1991	99.74
1992	101.31
1993	102.81
1994	104.43
1995	106.19
1996	116.14
1997	126.8
1998	138.4
1999	151.11
2000	165.21
2001	174.61
2002	185.01
2003	196.83
2004	209.68
2005	223.56
2006	233.42
2007	243.55
2008	254.07
2009	265.33
2010	277.67
2011	283.72
2012	290.33
2013	296.95
2014	303.75
2015	310.81
2016	318.02