Year	Number
2011	-1.2734762430191
2012	-1.41670286655426
2013	-1.53562760353088
2014	-1.85091555118561
2015	-1.89496612548828
2016	-1.97679388523102
2017	-1.97194159030914
2018	-1.98611116409302
2019	-2.00850081443787
2020	-1.97039973735809
2021	-2.07081079483032
2022	-2.05544900894165