Year	Number
1998	21.01056
2000	14.74115
2001	14.76133
2003	14.85734
2005	10.89688
2006	10.73176
2007	10.42117
2008	10.08246
2009	9.62744
2010	9.3561
2011	8.58714
2012	8.34085
2013	9.91525
2014	9.89858
2015	9.78107
2016	9.63181
2017	9.51267