Year	Number of
1990	84.21
1991	86.13
1992	86.31
1993	84.45
1994	83.29
1995	83.49
1996	89.11
1997	97.12
1998	108.33
1999	114.92
2000	119.5
2001	118.38
2002	119.57
2003	117.35
2004	117.95
2005	120.21
2006	126.99
2007	133.84
2008	139.34
2009	144.41
2010	148.76
2011	152.3
2012	156.11
2013	162.34
2014	169.89
2015	179.46
2016	189.6