The service sector in Canada is vast and multifaceted, employing about three quarters of Canadians and accounting for 70% of GDP. The largest employer is the retail sector, employing almost 12% of Canadians. The retail industry is concentrated mainly in a small number of chain stores clustered together in shopping malls. In recent years, there has been an increase in the number of big-box stores, such as Wal-Mart (of the United States), Real Canadian Superstore, and Best Buy (of the United States). This has led to fewer workers in this sector and a migration of retail jobs to the suburbs.