Languages of Catalonia
The main cause of Spanish and Catalan social bilingualism in modern Catalonia was large-scale migration from the rest of Spain during the 20th century, as Catalonia started a significant industrialization which demanded an increased workforce from elsewhere. Spanish has historically been spoken among a minority of civil servants born in other regions in Spain and among segments of the wealthiest bourgeoisie. Spanish has also been spoken as a second language by most Catalans, as it has been the only official language over long periods since the eighteenth century.
Languages of Catalonia
According to the linguistic census elaborated by the Government of Catalonia corresponding to 2008, 45.92% of citizens over 15 years old declared Spanish as their [only] habitual language of use, versus 35.64% for Catalan, with 11.95% of complete bilinguals; a larger number claims Catalan as "their own language" (37.25% Catalan compared to 46.53% Spanish and 8.81% bilinguals).