Year	Number of
1990	70.25
1991	72.21
1992	74.7
1993	77.3
1994	79.47
1995	80.88
1996	79.62
1997	83.27
1998	85.96
1999	90.35
2000	95.58
2001	98.55
2002	100.9
2003	106.5
2004	111.89
2005	114.84
2006	120.27
2007	127.85
2008	132.74
2009	141.94
2010	145.72
2011	154.37
2012	160.57
2013	166.31
2014	175.47
2015	179.26
2016	184.56