Upon its founding in 1949, West Germany had eleven states. These were reduced to nine in 1952 when three south-western states (South Baden, Württemberg-Hohenzollern, and Württemberg-Baden) merged to form Baden-Württemberg. From 1957, when the French-occupied Saar Protectorate was returned and formed into the Saarland, the Federal Republic consisted of ten states, which are referred to as the "Old States" today. West Berlin was under the sovereignty of the Western Allies and neither a Western German state nor part of one. However, it was in many ways de facto integrated with West Germany under a special status.
How many states did West Germany add after it's founding in 1952?