Excel 2013. All cells in this spreadsheet are formatted as Time.

Column E is the Start Time.
Column F includes minutes to deduct from the Elapsed time.
Column G contains no data.
Column H includes minutes to deduct from the Elapsed time.
Column I is the End Time.

Column J contains cells with this formula to calculate the Elapsed Time of the values in the row:
For example: =IF(I16=E16,I16-E16-F16-H16,I16-F16-H16+1-E16)

E F G H I J
16 6:00 AM 0:15 0:15 9:00 AM 2:30
17 11:45 PM 0:30 1:30 7:00 AM 5:15
18 11:00 PM 0:15 0:15 9:00 AM 9:30

How can I calculate the average of the elapsed times in Column J?