The reason you cannot find statistics on GDR unemployment is that there were not any. The SED claimed that unemployment was a symptom of bourgeois capitalism and sought full employment via its vast network of state enterprises. Therefore, the GDR economy was often highly over-staffed and very unproductive. The state control over the economy distorted prices by restricting products. What plagued the GDR was not so much unemployment as underemployment. People had jobs, but there was very little their wages could buy. This is part of the reason why the post-unification economic transition was so rough in the GDR, these state-run enterprises were inherently inefficient and their workerforce needed to get habituated to Western models of employment.