It was 12,8% effective.

What the hell does that mean? Well, it menas that on average, over the 7 battles I have found reliable figures for armored losses by cause, artillery accounted for 12,8% of armored losses. Anti-tank guns in various forms account for 68,7% of armored losses, air attack 7,4% and infantry AT weapons (panzerschrecks, Bazookas, mines etc) account for 4,8% of armored losses and finally 6,3% were caused by either unknown causes or multiple types where the primary cause could not be determined (for example a tank that showed both mine damage and anti-tank gun damage where it could not be determined which weapon knocked the tank out).

However, it should be noted that we only have reasonable figures from 7 battles in all of WW2 and in only 4 of those cases was the data compiled by operations research personel using rigid and uniform criteria for the determination of losses. In the other three the data was compiled using field reports. It should also be noted that the numbers differ quite a lot between battles depending on theater and situation. The highest percentage (and alost the largest numbers of total tanks destroyed) was reported by the Soviet 1st Tank Army at the the Battle of Kursk where the figure reported was 14,8% of tanks lost to artillery.

The lowest recorded was for the German armor at Elsenbord Ridge which was the Sixth Panzer Army in Kampfgruppe Peiper which reported only 5,9% of armored losses to artillery. However, at Elsenborg Ridge the figures might be explained by US use of proximity fuses along with the presence of the 612th and 820th Tank Destroyer battalions and great air support. A medium or heavy tank essentially requires a direct hit from artillery to be knocked out, an air detonating proximity fuse shell is less likely to deliver such a hit (although it is much more effective against soft targets).

These figures do not include abandonned tanks because if we were to include those we would have to account for a lot of German armor abandoned due to the collapsing Falaise pocket and pockets in Normandy where many of the tanks may not in fact have been knocked out, they were abandoned for other reasons such as lack of fuel or time.