Complex sentence: In 1951,46% of the manufacturing jobs in the city were in shipbuilding, however by 1966 this had fallen down to 14%, drastically reducing the workforce of the dockyard.
Split into simpler sentences: In 1951,46% of the manufacturing jobs in the city were in shipbuilding. By 1966 this had fallen down to 14%, drastically reducing the workforce of the dockyard.