Trouble with drop down box on pivotchart.
 

I have made a pivotchart with "time" as a field on the x-axis. When I click
the drop down box for "Time" I have 1440 minutes for all the minutes in a
day. I would like to keep the by-minute generation data, but when I click
the "Time" drop down box I would like to be a vle to select 1 hour or 60
minutes at a time so I do not have to select all 60 minutes one at a time.
Is there any way to solve this issue?