Year	Number
1986	1.564662128138741
1987	1.968093941223461
1988	2.227523699459166
1989	2.8515034860739354
1990	3.116993305343727
1991	3.2066281968773493
1992	3.1864672220193917
1993	2.6997158328429425
1994	3.1014247925258194
1995	2.7595658453548055
1996	3.236976674494207
1997	3.7755735190861777
1998	3.4253532186321145
1999	3.8130906937295896
2000	4.124335990852846
2001	3.1997329789277575
2002	3.03764833200827
2003	3.6709991381450364
2004	3.7636013684601477
2005	4.17394784188132
2006	3.457819935777745
2007	3.147921103348211
2008	2.4155110494547194
2009	2.572627848035761
2010	2.4866831184185023
2011	2.558194336640415
2012	2.48518368223946
2013	2.815659412954652
2014	2.8545075102500697
2015	2.605590829823111
2016	2.523002026872608
2017	2.6112107958868775
2018	2.4944670419686754
2019	2.5987350403823655
2020	2.210257930176752
2021	1.9812060324012954
2022	2.005967711534185