Query: How many Greek shipping companies were in operation in 2011?
Context: Earnings from shipping amounted to €14.1 billion in 2011, while between 2000 and 2010 Greek shipping contributed a total of €140 billion (half of the country's public debt in 2009 and 3.5 times the receipts from the European Union in the period 2000–2013). The 2011 ECSA report showed that there are approximately 750 Greek shipping companies in operation.