Year	Number
1998	42.11771
1999	43.04644
2000	45.03028
2001	45.08008
2002	41.42316
2003	36.043
2004	33.74316
2005	28.26998
2006	28.25779
2007	28.59999
2008	29.56366
2009	29.92512
2010	31.04891
2011	32.90159
2012	34.01583
2013	36.87466
2016	41.05007
2017	36.68254