Year	Number
1980	9.298499399712624
1981	6.085872549457506
1985	10.180747396896955
1990	9.326544760247119
1991	8.303159125357222
1997	10.077055309742246
2000	13.09709539402221
2001	12.653381369958641
2002	10.231585982741638
2003	14.031130596007763
2004	13.578733018058902
2005	14.62640222905562
2006	17.617627382615357
2007	18.836206907869833
2008	17.15218880256316
2009	19.532030112962907
2010	18.00618807147164
2011	31.01989481255518
2012	19.384698444340778
2013	16.349954597825292
2014	14.926831383819554
2015	18.925140086074375
2016	27.357216267770607
2017	24.922501284499592
2018	21.977643319700025
2019	17.572087461232908
2020	27.871033067406348
2021	18.797743262685117
2022	11.549504347505438