Finding sum for last 180 days with a twist

[CodePest]

I have a table that totals absences for the last 18 months. My table includes collapsible rows and headings with a total row for 2017 and 2018. There is also a total row for each month. Because of my layout my column of days is not consistent. I've included an example below:

[TABLE="width: 500, align: center"]
<tbody>[TR]
[TD="align: center"]A[/TD]
[TD="align: center"]B[/TD]
[TD="align: center"]C[/TD]
[TD="align: center"]D[/TD]
[/TR]
[TR]
[TD]2018[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]Jan 2018[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD][/TD]
[TD]Date[/TD]
[TD]Absence[/TD]
[TD]180 Day Total[/TD]
[/TR]
[TR]
[TD][/TD]
[TD]1/1/2018[/TD]
[TD]1[/TD]
[TD]1
[/TD]
[/TR]
[TR]
[TD][/TD]
[TD]1/2/2018[/TD]
[TD][/TD]
[TD]1[/TD]
[/TR]
[TR]
[TD][/TD]
[TD]1/3/2018[/TD]
[TD][/TD]
[TD]1[/TD]
[/TR]
[TR]
[TD][/TD]
[TD]1/4/2018[/TD]
[TD]1[/TD]
[TD]2[/TD]
[/TR]
[TR]
[TD][/TD]
[TD]1/5/2018
[/TD]
[TD][/TD]
[TD]2[/TD]
[/TR]
[TR]
[TD][/TD]
[TD]Total[/TD]
[TD]2[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]February 2018[/TD]
[TD]2/1/2018[/TD]
[TD][/TD]
[TD]2[/TD]
[/TR]
[TR]
[TD][/TD]
[TD]2/2/2018[/TD]
[TD][/TD]
[TD]2[/TD]
[/TR]
[TR]
[TD][/TD]
[TD]2/3/2018[/TD]
[TD]1[/TD]
[TD]3[/TD]
[/TR]
[TR]
[TD][/TD]
[TD]2/4/2018[/TD]
[TD][/TD]
[TD]3[/TD]
[/TR]
[TR]
[TD][/TD]
[TD]2/5/2018[/TD]
[TD][/TD]
[TD]3[/TD]
[/TR]
[TR]
[TD][/TD]
[TD]Total[/TD]
[TD]1[/TD]
[TD][/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
</tbody>[/TABLE]


While totaling the month and years are easy, I also need to include a column (D) with a running 180 day total that takes into account the breaks for the total rows. I'm just not sure what equation to use. I thought maybe SUMIF but I'm not entirely sure how to execute it. Any help would be appreciated.

Would there be a way to create an equation that calculates a 180 days back from the corresponding date on the running total line, and then finds and matches any dates with absences?

 

[CodePest]

ONE MORE THING, absences can either be 0.5 or 1

 

[CodePest]

The solution was actually quite simple:

SUMIFS(SUMRANGE,DATERANGE,">="&DATE-180,DATERANGE,"<="&DATE)

SUMRANGE represents the column of cells containing the relevant values(Absences in this example). DATERANGE is the range of cells containing dates to consider. DATE is the corresponding date or the date in consideration. This calculation returns the last 180 days of absences starting from a specific DATE.

Hopefully this is helpful to someone else.