Year	Number
2001	1.9742080082362825
2002	2.1335057224959906
2003	2.285217285754751
2004	2.244850928047064
2005	2.1764374111226967
2006	2.0649191736706407
2007	2.2790540003925623
2008	1.9989687015223754
2009	4.0913780480104505
2010	3.8487760334658176
2011	4.408480404112503
2012	5.060215541081702
2013	4.783141812757749
2014	6.358930222819357
2015	7.597816656509872
2016	9.205778435187298
2017	8.982320487729975
2018	6.200496732593561
2019	6.861712218412568
2020	6.909847154737382
2021	5.92653380984777
2022	5.4798030918599085