sample data

data.json

{
  "1960":316.91,
  "1961":317.64,
  "1962":318.45,
  "1963":318.99,
  "1964":319.62,
  "1965":320.04,
  "1966":321.38,
  "1967":322.16,
  "1968":323.04,
  "1969":324.62,
  "1970":325.68,
  "1971":326.32,
  "1972":327.45,
  "1973":329.68,
  "1974":330.18,
  "1975":331.11,
  "1976":332.04,
  "1977":333.83,
  "1978":335.4,
  "1979":336.84,
  "1980":338.75,
  "1981":340.11,
  "1982":341.45,
  "1983":343.05,
  "1984":344.65,
  "1985":346.12,
  "1986":347.42,
  "1987":349.19,
  "1988":351.57,
  "1989":353.12,
  "1990":354.39,
  "1991":355.61,
  "1992":356.45,
  "1993":357.1,
  "1994":358.83,
  "1995":360.82,
  "1996":362.61,
  "1997":363.73,
  "1998":366.7,
  "1999":368.38,
  "2000":369.55,
  "2001":371.14,
  "2002":373.28,
  "2003":375.8,
  "2004":377.52,
  "2005":379.8,
  "2006":381.9,
  "2007":383.79,
  "2008":385.6,
  "2009":387.43,
  "2010":389.9,
  "2011":391.65,
  "2012":393.85,
  "2013":396.52,
  "2014":398.65,
  "2015":400.83,
  "2016":404.24,
  "2017":406.55,
  "2018":408.52,
  "2019":411.43
}