Man Power Histogram from actuals

Dear all

 I prepared a man power histogram from actual dates ( actual start and expected date to finish ). there are activities alredy started and compleated 50% and consumed 50 % of man power, but the generated man power histogram  not showing any  reduction of man power in started activities . I really want to filter the consumed man power from the activity and show a realistic histogram , please give your suggestions  to create  a man power histogram in P3 by filtering man power  that already consumed

thanks