Mark Adkin's "Trafalgar Companion" pg 302 has a comparison. Adkin also wrote similar massive and well illustrated book on on Waterloo & Gettysburg.
"At Waterloo a total of 497 guns were deployed by the British, Prussian and French - at Trafalgar there were 4662 guns. One discharge of all the artillery at Waterloo would total 1,5 tons of metal. compared to the combined 47 tons at Trafalgar. The French Grand Battery (80 guns) could fire 0.25 tons in volley whereas a single 74 , such as Mars, could fire 0.75 tons in a (two sided) broadside."
Of course at Waterloo you also had 200,000 infantry and Cavalry all shooting as well - although none of them were as effective as a single French marksman on the Redoutable.................