Summing issue

[Blake 7]

Hey Guys how's it going, hope all is well. Just came back from Hillhead in Devon, nr Dartmouth and Dittisham (Dittisham being best crabbing place in the uk imho)!

Now back at work and trying to overcome the usual stuff!

I am a bit lost here. I have attached a spreadsheet showing data and desired output.

I have a list of dates (col a) and a number of cancellations on that date (col b) (col b represents a period of days)

For each date during the min and max date of col I need to know how many cancellations there were. All cancellations in col b are rolled over or cumulative. ie if the date is 01/05/2010 and col b says 4 then this counts as one cancellation for each iof the following dates 01/05/2010 thru 04/05/2010

PLEASE NOTE - this is not a sumproduct of date col a and number of cancellations in col B.

This issue is easier to describe via example. please see attached.

Thanks for looking - any q's pls come back to me.