What's the use of '% to GDP' type of variables? In my study I will look for the relationship between the Gini coefficient and trade, FDI and other variables. However, as I was regressing it... the result turn out to be insignificant. My data that I used then were 'trade as a percentage to GDP' and 'FDI as a percentage to GDP'.

On the other hand, when I regress it with just the total of trade and FDI... it brings a somewhat significant result.

Can I drop the 'as a perentage of GDP'? And just use the total trade and FDI without that?

Plus I only have 16 years worth of data, though.
Imagine that I am trying to determine whether eating corn has any effect on your height. I see that in the US, total corn consumption is 20 million tons per year (made up number, all others will be made up as well) and adding up the heights of the 300 million citizens we get 500 million meters. Similar statistics for France are 4 million tons per year and 100 million meters. 

Total American corn consumption was higher, as well as total American height.
Is this because corn has an effect on height? Or is it that both statistics are likely to be proportional to the size of the country (measured here by population)?

Depending on what your exact hypothesis is, you may want to filter out size effects by measuring these statistics of the national accounts as % of GDP.