I never saw this one before. Openness:
At FRED the notes on it say:
Exports plus Imports divided by GDP is the total trade as a percentage of GDP. More information is available at http://pwt.econ.upenn.edu/Documentation/append61.pdf
Exports plus imports. Openness. Here's the same data on a log scale:
'If nations can learn to provide themselves with full employment by their domestic policy....there would be no longer a pressing motive why one country need force its wares on another or repulse the offering of its neighbour...so as to develop a balance of trade in its own favour. International trade would cease to be what it is, namely a desperate expedient to maintain employment at home by forcing sales on foreign markets and restricting purchases which, if successful, will merely shift the problem of unemployment to the neighbour which is worsted in the struggle'.