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In this article, we compute the value of patent protection obtained through application for patents at the French Patent Office (INPI), using patent renewal data and values of renewal fees payable to maintain patents in force, over the 1951-2000 period. Simulations of patent protection value, based on our econometric estimations for the 1951-1993 period, demonstrate that average patent values increased continuously and substantially during this period and that the patent value distribution function is strongly asymmetric. Interpreting this increase in the average value of patent protection as evidence of improvement in the intrinsic quality of innovations protected by patents, we explain a substantial portion of the decrease in the patents-to-R&D ratio by a focusing of R&D on more highly-valued objectives.