Germany simply didn't build many and lost quite a few early in the war.
Discounting the training cruiser Emden, the Germans built five 15cm (really 149.1mm) light cruisers in the interwar era - all built under the limits of the Versailles treaty, which limited their standard displacement to 6,000 tons.
Due to the low displacement allowed for them, and the relatively heavy gun armament the Germans tried to fit on this displacement (nine 15cm guns), they were not very satisfactory ships, and their wartime luck was not great. Two were lost in the invasion of Norway - Königsberg to air attack and Karlsruhe to a submarine. Their sister, Köln, survived and actually spent much of the war in Norway, but did not get to take part in major actions.
Leipzig was crippled by torpedo attack late in 1939 and spent most of 1940 under repair. After this she was mostly deployed in the Baltic against the Soviets, but spent much of 1943 and 1944 inactive, mostly down to refits and crew issues. Shortly after returning to service, she was rammed by Prinz Eugen and almost cut in half. The damage was bad enough to ensure she was never repaired, and instead used as a floating battery for the rest of the war.
Nürnberg, the last German light cruiser, was also torpedoed in late 1939, but was repaired by spring of 1940.