Year	Number of
1990	79.72
1991	79.01
1992	77.95
1993	76.92
1994	76.45
1995	76.92
1996	78.67
1997	81.82
1998	85.99
1999	90.52
2000	95.17
2001	98.77
2002	102.51
2003	106.55
2004	110.99
2005	116.06
2006	120.93
2007	126.14
2008	132.11
2009	138.55
2010	145.58
2011	152.11
2012	159.3
2013	166.84
2014	174.51
2015	182.2
2016	189.11