Year	Number of Years
1960-01-01	66.0552926829268
1961-01-01	66.5970243902439
1962-01-01	67.0214146341464
1963-01-01	67.3399024390244
1964-01-01	67.5665121951220
1965-01-01	67.7188536585366
1966-01-01	67.8125121951220
1967-01-01	67.8601463414634
1968-01-01	67.8743414634146
1969-01-01	67.8671219512195
1970-01-01	68.1336585365854
1971-01-01	68.3765853658537
1972-01-01	68.3085365853659
1973-01-01	68.2946341463415
1974-01-01	68.3202439024390
1975-01-01	67.7239024390244
1976-01-01	67.4875609756098
1977-01-01	67.3763414634146
1978-01-01	67.3909756097561
1979-01-01	67.1143902439024
1980-01-01	67.0339024390244
1981-01-01	67.2639024390244
1982-01-01	67.8060975609756
1983-01-01	67.6526829268293
1984-01-01	67.2026829268293
1985-01-01	67.8568292682927
1986-01-01	69.3897560975610
1987-01-01	69.4400000000000
1988-01-01	69.4643902439024
1989-01-01	69.1717073170732
1990-01-01	68.8860975609756
1991-01-01	68.4743902439024
1992-01-01	66.8731707317073
1993-01-01	64.9358536585366
1994-01-01	64.4670731707317
1995-01-01	64.6907317073171
1996-01-01	65.8541463414634
1997-01-01	66.6987804878049
1998-01-01	67.0297560975610
1999-01-01	65.9821951219512
2000-01-01	65.4836585365854
2001-01-01	65.3834146341463
2002-01-01	65.1287804878049
2003-01-01	65.0478048780488
2004-01-01	65.4709756097561
2005-01-01	65.5297560975610
2006-01-01	66.7275609756098
2007-01-01	67.5868292682927
2008-01-01	67.9492682926829
2009-01-01	68.6846341463415
2010-01-01	68.8412195121951
2011-01-01	69.6839024390244
2012-01-01	70.0721951219512
2013-01-01	70.5787804878049
2014-01-01	70.7436585365854
2015-01-01	71.1682926829268
2016-01-01	71.5929268292683