R version 2.15.2 (2012-10-26) -- "Trick or Treat"
Copyright (C) 2012 The R Foundation for Statistical Computing
ISBN 3-900051-07-0
Platform: i686-pc-linux-gnu (32-bit)

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> x <- c(86.86,86.79,82.52,86.87,81.62,82.66,89.87,92.04,79.74,77.75,79.12,76.37,75.01,77.6,77.81,81.7,76.47,74.72,84.43,86.72,70.99,75.43,74.14,73.3,71.97,69.27,74.13,76.4,72.26,72.1,87.82,91.62,82.69,85.76,86.87,93.09,83.73,84.49,87.37,89.13,83.2,83.77,93.68,93.09,88.59,87.88,87.89,89.38,89.13,89.58,90.22,91.44,91.04,92.1,97.54,99.12,100,99.68,100.08,99.9,99.63,99.45,99.63,99.46,96.91,97.65,102.1,103.57,104.59,104.79,101.31,104.8)
> par4 = '12'
> par3 = 'prijs vliegtuigticket'
> par2 = 'http://www.nbb.be/belgostat/PresentationLinker?TableId=696000084&Lang=N'
> par1 = 'prijs vliegtuigticket'
> ylimmax = as.numeric(december)
Error: object 'december' not found
Execution halted