Year	number
2005	40.395348837209305
2006	40.06818181818182
2007	39.90909090909091
2008	39.77272727272727
2009	39.72727272727273
2010	39.43181818181818
2011	39.09090909090909
2012	38.55555555555556
2013	38.84782608695652
2014	39.08695652173913
2015	38.78260869565217
2016	38.32608695652174
2017	37.32608695652174
2018	37.80434782608695
2019	36.71739130434783