Year	Number
1996	1.517697930336
1998	1.46729826927185
2000	1.59303331375122
2002	1.55290365219116
2003	1.57245707511902
2004	1.78360843658447
2005	1.68709695339203
2006	1.4940721988678
2007	1.4602267742157
2008	1.46308124065399
2009	1.46526706218719
2010	1.48671269416809
2011	1.50755143165588
2012	1.60069715976715
2013	1.57370555400848
2014	1.54194664955139
2015	1.54360699653625
2016	1.53178548812866
2017	1.55936217308044
2018	1.58888149261475
2019	1.56277894973755
2020	1.60945093631744
2021	1.60982477664948
2022	1.60161948204041