Robust regression in matlab

I did robust regression in matlab. The thing is I can't display the correlation coefficient in my graph as (R^2 = ??). Can you help me with that? here is the regression part which am working on.

for ss =1:size(R,2);

         [bls,sts] = robustfit(R(:,ss),f(:,ss));
         scatter(R(:,ss),f(:,ss),'filled'); 
         plot(R(:,ss),bls(1)+bls(2)*R(:,ss))
  end;