Year	Number
1987	7.715474156137006
1988	13.365926921346212
1989	7.783088709821954
1990	17.31334952173752
1991	7.236290241984242
1992	3.7991525083368884
1993	3.9504399864228463
1994	2.5410842423584055
1995	4.134137507370743
1996	3.8594806196161096
1997	2.3798849328062426
1998	3.643508326466781
1999	4.833304255718758
2000	3.5259297794678908
2001	2.1730267676897954
2002	1.867239888707075
2003	1.73549176824093
2004	1.5383506110213427
2005	1.541292010303135
2006	1.304803799757439
2007	1.5201823897143998
2008	1.7379079731936764
2009	1.4025122461218877
2010	1.3278695962291378
2011	1.473806408315463
2012	1.3703515619808477
2013	1.486514195111122
2014	1.8091414600660392
2015	1.846508331128466
2016	1.936968421407149
2017	1.9437449466993615
2018	2.2948516375849946
2019	2.3740633665234503
2020	2.200261871133344
2021	2.614695344666515
2022	2.3046399846875056
2023	1.9997391749067615