The Germans spent quite the resources on the Flak arm. More than half a million men were in service as early as 1940, manning not just the guns, but also the reflectors, communications, etc*. The shells manufactured for the guns of 8,8 cm and bigger went between 400 000 and, from 1941, up to 1400 000 per month. Before the BoB, there was something like 10000 light AA and almost 4000 heavy guns under LW control. In 1942, the Gemans were spending 27-28% of total Wehrmacht waepon budget, and 15-17% of total W. ammo budget*. Most of the Flak forces being deployed west of Berlin.
In second half of 1942, RAF estimated that losses due to Flak were 193 aircraft, the damaged A/C numbered 918. Basically, one kill and five damaged aircraft per 24 hours. That was done by 866 heavy Flak batteries (4 guns each = 3464 guns) and 621 light batteries, available in Germany proper and in the occupied West. Introduction of radar meant that the ratio of heavy shells expanded per kill dropped down to 4000.
RAF loosing more aircraft due to mechanical issues, bad weather and faulty navigation, than the Flak in 1941-42?
The RAF's bomber campaign against Germany was pretty effective way to tie up significant German resources even in the days when no targets wee hit.
*for the Flak forces