Year	Number of
1990	81.59
1991	83.07
1992	84.33
1993	85.42
1994	86.86
1995	88.89
1996	87.69
1997	86.9
1998	86.37
1999	85.7
2000	84.84
2001	86.85
2002	88.53
2003	90.25
2004	91.81
2005	93.46
2006	94.53
2007	95.91
2008	97.37
2009	99.29
2010	101.7
2011	104.43
2012	107.43
2013	110.67
2014	113.94
2015	117.35
2016	120.95