Year	number
2005	35.283018867924525
2006	34.41509433962264
2007	33.611111111111114
2008	32.2037037037037
2009	31.944444444444443
2010	31.62962962962963
2011	30.74074074074074
2012	30.767857142857142
2013	31.083770491803282
2014	30.05098360655738
2015	29.739508196721314
2016	29.313278688524587
2017	26.93344262295082
2018	27.064590163934426
2019	26.52360655737705