Year	Number of
1990	74.45
1991	76.47
1992	78.67
1993	81.01
1994	83.53
1995	86.35
1996	86.33
1997	86.57
1998	86.95
1999	87.46
2000	88.17
2001	87.21
2002	86.48
2003	85.84
2004	85.36
2005	85.11
2006	85.6
2007	86.12
2008	86.86
2009	87.76
2010	88.89
2011	90.23
2012	91.83
2013	93.52
2014	95.36
2015	97.33
2016	99.35