Year	Number
1996	-2.17516660690308
1998	-2.10229182243347
2000	-2.17394614219666
2002	-1.58768701553345
2003	-1.17576801776886
2004	-0.945146262645721
2005	-1.2288156747818
2006	-1.47365152835846
2007	-1.44011056423187
2008	-1.52779507637024
2009	-1.50775218009949
2010	-1.47831559181213
2011	-1.47410047054291
2012	-1.37553513050079
2013	-1.39949083328247
2014	-1.35930466651917
2015	-1.39618384838104
2016	-1.29025280475616
2017	-1.38897216320038
2018	-1.50134539604187
2019	-1.51861417293549
2020	-1.60950922966003
2021	-1.66956210136414
2022	-1.87955236434937