Year	number
2005	40.95652173913044
2006	41.108695652173914
2007	40.608695652173914
2008	40.43478260869565
2009	40.5
2010	39.82608695652174
2011	39.369565217391305
2012	39.276595744680854
2013	39.276666666666664
2014	37.962941176470586
2015	37.37470588235294
2016	36.060980392156864
2017	33.64588235294118
2018	33.35176470588235
2019	31.21450980392157