Year	number
2003	11.235955056179776
2004	10.824742268041238
2005	10.741071428571429
2006	10.605263157894736
2007	10.236842105263158
2008	9.719298245614034
2009	9.234782608695653
2010	9.034782608695652
2011	8.660869565217391
2012	8.601694915254237
2013	8.492063492063492
2014	8.341269841269842
2015	8.181102362204724
2016	7.94488188976378
2017	7.748031496062992
2018	7.409448818897638
2019	7.228346456692913