Univariate portfolio returns based on R&D

Hi guys.

I am trying to look for a link between R&D/Revenue and returns, more specific, does more R&D/Revenue equal higher returns?

I am trying to make 10 portfolios, based on their amount of R&D, så the 10th portfolio has the stocks with the highest R&D and the 1st portfilio has the stocks with the lowest R&D.

Then i need to find out, how much return the portfolios has made over the period (I am using data from primo 2000 to ultimo 2019).

This is where i get stuck -- how do i incorporate the returns with the portfolios?