Year	Number
2004	7.044939463265746
2005	6.8222265101330635
2006	9.019000405134156
2007	9.66579382459015
2008	9.552498652389428
2009	8.383157042596086
2010	7.874473479501725
2011	8.290628255475578
2012	8.34485066813755
2013	8.309370964611212
2014	7.251192456073886
2015	7.192217056837381
2016	8.495540758031344
2017	8.46940251466131
2018	8.668547877470846
2019	7.739023842455806
2020	8.634829744836622
2021	9.427079896383045
2022	11.156045319300933