Year	Number
1985	23.7096
1986	23.33455
1990	25.37997
1991	25.58859
1992	24.41457
1994	23.04261
1996	20.59208
1997	19.99244
1998	19.9799
1999	19.10299
2000	18.71186
2001	22.1794
2002	26.4663
2003	21.08209
2004	27.65356
2005	36.30216
2006	26.98748
2008	24.93864
2009	25.36685
2010	24.43635
2011	20.09592
2012	17.5769
2013	17.59318
2014	17.2181
2015	16.98876
2016	21.65401
2017	22.01485
2018	29.80271