Year	Number
1991	1.9061702065071202
1992	2.8898806967978725
1993	2.47844017155247
1994	3.5522257234069925
1995	3.9420822780711355
1996	4.004690241378034
1997	3.1157167019198275
1998	1.5119371534767896
2000	2.087769979399108
2001	1.6955234892241742
2002	1.5867526205691385
2003	1.9649294139580185
2004	5.9809381152734185
2005	5.698754152828475
2006	19.03081570711508
2007	17.357092651906562
2008	18.429203158064915
2009	2.8175480217981326
2010	6.009999089503585
2011	1.9455920637067274
2012	2.0880302074309545
2013	2.1397733630974973
2014	2.0876130651062006
2015	3.3421616495021618
2016	2.451101179428438
2017	2.4243072122203393
2018	2.1190516282513525
2019	2.3113159996829666
2020	2.5070452498491633