observ ation_dateEXCHUS1981-01-011.55181981-02-011.61311981-03-011.63141981-04-011.66601981-05-011.72701981-06-011.76051981-07-011.76471981-08-011.80031981-09-011.75421981-10-011.75761981-11-011.74091981-12-011.74051982-01-011.77131982-02-011.82001982-03-011.84291982-04-011.85651982-05-011.81231982-06-011.90141982-07-011.93001982-08-011.94321982-09-011.95671982-10-011.98871982-11-012.00021982-12-011.94451983-01-011.92381983-02-011.96531983-03-011.98341983-04-011.99381983-05-011.98951983-06-011.99491983-07-011.99661983-08-011.98431983-09-011.98671983-10-011.96641983-11-011.99401983-12-011.99201984-01-012.04901984-02-012.06281984-03-012.06461984-04-012.09291984-05-012.18661984-06-012.21781984-07-012.29961984-08-012.37181984-09-012.54691984-10-012.64881984-11-012.67851984-12-012.79531985-01-012.81601985-02-012.83471985-03-012.85331985-04-012.84801985-05-012.85561985-06-012.86931985-07-012.88091 9 8 5 -0 8 -0 12 .9 0 9 31 9 8 5 -0 9 -0 12 .9 7 2 21 9 8 5 -1 0 -0 13 .0 7 8 21 9 8 5 -1 1 -0 13 .2 0 8 61 9 8 5 -1 2 -0 13 .2 0 9 51 9 8 6 -0 1 -0 13 .2 0 9 51 9 8 6 -0 2 -0 13 .2 1 5 21 9 8 6 -0 3 -0 13 .2 2 0 21 9 8 6 -0 4 -0 13 .2 1 4 31 9 8 6 -0 5 -0 13 .2 0 1 41 9 8 6 -0 6 -0 13 .2 1 1 51 9 8 6 -0 7 -0 13 .6 4 3 51 9 8 6 -0 8 -0 13 .7 1 2 91 9 8 6 -0 9 -0 13 .7 1 5 01 9 8 6 -1 0 -0 13 .7 2 5 71 9 8 6 -1 1 -0 13 .7 3 1 41 9 8 6 -1 2 -0 13 .7 3 1 41 9 8 7 -0 1 -0 13 .7 3 1 41 9 8 7 -0 2 -0 13 .7 3 1 41 9 8 7 -0 3 -0 13 .7 3 1 41 9 8 7 -0 4 -0 13 .7 3 1 41 9 8 7 -0 5 -0 13 .7 3 1 41 9 8 7 -0 6 -0 13 .7 3 1 41 9 8 7 -0 7 -0 13 .7 3 1 41 9 8 7 -0 8 -0 13 .7 3 1 41 9 8 7 -0 9 -0 13 .7 3 1 41 9 8 7 -1 0 -0 13 .7 3 1 41 9 8 7 -1 1 -0 13 .7 3 1 41 9 8 7 -1 2 -0 13 .7...
