Year	Number of
1990	74.57
1991	77.54
1992	82.22
1993	86.71
1994	90.58
1995	93.79
1996	94.48
1997	94.49
1998	96.13
1999	97.82
2000	99.9
2001	103.66
2002	107.67
2003	110.91
2004	114.36
2005	118.34
2006	121.44
2007	124.78
2008	127.94
2009	131.87
2010	136.85
2011	143.67
2012	150.96
2013	158
2014	164.98
2015	172.12
2016	181.66