pre_text: The company has consistently generated strong cash flow from operations, providing a source of funds ranging between $14.8 billion and $16.7 billion per year over the past three years. The company provides for additional liquidity through several sources: maintaining an adequate cash balance, access to global funding sources, committed global credit facilities and other committed and uncommitted lines of credit worldwide. The following table provides a summary of the major sources of liquidity for the years ended December 31, 2017 through 2019.
table: ($ in billions)
table: 2019 2018 2017
table: Net cash operating activities $14.8 $15.2 $16.7
table: Cash, restricted cash and short-term marketable securities $ 9.0 $12.2 $12.8
table: credit facilities $15.3 $15.3 $15.3
question: Analyse this data from a financial earnings document. What is the average of Committed global credit facilities?