Year	Number
1996	1.36694669723511
1998	1.21820557117462
2000	1.3139340877533
2002	1.34493565559387
2003	1.33109652996063
2004	1.31122982501984
2005	1.25764083862305
2006	1.22459959983826
2007	1.31538724899292
2008	1.33520579338074
2009	1.37714815139771
2010	1.41785252094269
2011	1.43484890460968
2012	1.44880962371826
2013	1.45678973197937
2014	1.54862999916077
2015	1.45646989345551
2016	1.39430689811707
2017	1.31977915763855
2018	1.33861649036407
2019	1.33622694015503
2020	1.3280041217804
2021	1.29238021373749
2022	1.34894239902496