The paragraph is followed by an incomplete phrase or sentence which summarizes the main idea of the paragraph. Choose the missing words of the phrase or sentence. 

The business travel and meetings organization in America attributes the recent increase to rising airfares, fuelled by energy prices, constrained capacity and relatively strong demand, higher lodging rates, and growing corporate demand. For example, it expects corporate spending on overseas trips to rise to $31.8 billion in 2011, a 9.1% increase on last year.
The price of （） continues rising in America in 2011.