There are many potential flaws and concerns with this type of bibliometric analysis, such as the skewed impact of individual papers, the impact of self-citations , the aggregate of citations across disciplines and more. That explains why is difficult to find such analysis nowadays, but I think it worth posting since it provides the "Big Picture" or the forest in the "can't see the forest for the trees" expression. And if you believe that "the devil is in the details" I suggest reading the original article dated back in 2004!
The scientific impact of nations
Nature 430, 311-316 (15 July 2004)
David A. King