Definitions of variables

 trade openness: the sum of imports and exports as a percentage of GDP

(imports+exports)/GDP

oil rents: "taking the total value of each country's annual oil and natural gas production, and subtracting the country-specific extraction costs, including the cost of capital."

3 years of moving average of x:

latex: \frac{x_{t-1}+x_{t}+x_{t+1}}{3}

2 years of moving average of x: (Xt+Xt-1)/2

similar terms: 

<increase>

lengthen

<decrease>

dampen