Year	Number of
1990	64.19
1991	64.88
1992	65.51
1993	65.82
1994	66.32
1995	67.13
1996	67.75
1997	68.65
1998	70.69
1999	72.67
2000	74.31
2001	74.44
2002	76.04
2003	78.19
2004	79.69
2005	80.69
2006	81.67
2007	82.23
2008	83.14
2009	84.14
2010	85.96
2011	87
2012	87.99
2013	88.92
2014	89.7
2015	90.37
2016	91.02