Year	Number of
1990	76.16
1991	79.14
1992	81.39
1993	83.34
1994	85.3
1995	87.66
1996	92.24
1997	97.74
1998	103.89
1999	110.67
2000	117.94
2001	123.58
2002	129.58
2003	135.95
2004	142.78
2005	150.19
2006	151.71
2007	153.35
2008	155.51
2009	157.96
2010	160.77
2011	165.15
2012	170.1
2013	175.57
2014	181.27
2015	187.1
2016	193.5