Macro to create average based on varying ranges

[Jedit]

I am trying to create a macro to take an average of various subsets of data embedded within a large set of data.

My current macro is:

Sub Step7()
'Relative turned on here
Selection.End(xlDown).Select
ActiveCell.Offset(1, 0).Range("A1").Select
ActiveCell.FormulaR1C1 = "Average"
ActiveCell.Offset(0, 1).Range("A1").Select
' Dont use autosum. type this formula:
Selection.FormulaR1C1 = "=AVERAGE(R2C:R[-1]C)"
Selection.AutoFill Destination:=ActiveCell.Range("A1:G1"), Type:= _
xlFillDefault
ActiveCell.Range("A1:C1").Select
'Relative turned off here
ActiveCell.Rows("1:1").EntireRow.Select
ActiveCell.Activate
Selection.Font.Bold = True
Cells.Select
Selection.Columns.AutoFit
Range("A1").Select



End Sub


The macro reads my set of data and produces an average value at the end of the entire data list or upon a break of data.

However, the macro calculates the average from all data beginning at the top of the list. What I would like for the macro to do is:

Formulate an average based upon the active cell and break of information.

I need to use this macro for multiple data sets and multiple ranges of data (3 rows, 8 rows and 24 rows)

I believe this way I can still use the same macro to calculate the average for each subsection of data located in the same data set.

The following table is some of the data i need to calculate the average for:

I need to create average for 3 hour periods, 8 hours period, and 24 hour periods and I think my macro will work if I can make it so the range for my macro is from the active cell to the break of information ( which I would need to insert manually)

Thank you for any assistance you can provide.

Jedit
[TABLE="class: grid, width: 500"]
<tbody>[TR]
[TD]date/time[/TD]
[TD]conc[/TD]
[TD]flow[/TD]
[TD]w/s[/TD]
[TD]w/d[/TD]
[TD]at[/TD]
[TD]rhx[/TD]
[/TR]
[TR]
[TD]11/15/2012 19:00[/TD]
[TD].02[/TD]
[TD]16.7[/TD]
[TD].3[/TD]
[TD]351[/TD]
[TD]18.3[/TD]
[TD]41[/TD]
[/TR]
[TR]
[TD]11/15/2012 20:00[/TD]
[TD].019[/TD]
[TD]16.7[/TD]
[TD].3[/TD]
[TD]359[/TD]
[TD]18.7[/TD]
[TD]42[/TD]
[/TR]
[TR]
[TD]11/15/2012 21:00[/TD]
[TD].014[/TD]
[TD]16.7[/TD]
[TD].3[/TD]
[TD]354[/TD]
[TD]19.2[/TD]
[TD]42[/TD]
[/TR]
[TR]
[TD]11/15/2012 22:00[/TD]
[TD].019[/TD]
[TD]16.7[/TD]
[TD].3[/TD]
[TD]29[/TD]
[TD]19.7[/TD]
[TD]43[/TD]
[/TR]
[TR]
[TD]11/15/2012 23:00[/TD]
[TD].015[/TD]
[TD]16.7[/TD]
[TD].3[/TD]
[TD]48[/TD]
[TD]20[/TD]
[TD]44[/TD]
[/TR]
[TR]
[TD]11/16/2012 0:00[/TD]
[TD].018[/TD]
[TD]16.6[/TD]
[TD].3[/TD]
[TD]34[/TD]
[TD]20.2[/TD]
[TD]45[/TD]
[/TR]
[TR]
[TD]11/16/2012 01:00[/TD]
[TD].014[/TD]
[TD]16.5[/TD]
[TD].3[/TD]
[TD]11[/TD]
[TD]20.4[/TD]
[TD]45[/TD]
[/TR]
[TR]
[TD]11/16/2012 02:00[/TD]
[TD].015[/TD]
[TD]16.7[/TD]
[TD].3[/TD]
[TD]58[/TD]
[TD]20.4[/TD]
[TD]46[/TD]
[/TR]
[TR]
[TD]11/16/2012 03:00[/TD]
[TD].021[/TD]
[TD]16.7[/TD]
[TD].3[/TD]
[TD]1[/TD]
[TD]20.2[/TD]
[TD]47[/TD]
[/TR]
[TR]
[TD]11/16/2012 04:00[/TD]
[TD].018[/TD]
[TD]16.6[/TD]
[TD].3[/TD]
[TD]24[/TD]
[TD]19.8[/TD]
[TD]48[/TD]
[/TR]
[TR]
[TD]11/16/2012 05:00[/TD]
[TD].017[/TD]
[TD]16.7[/TD]
[TD].3[/TD]
[TD]26[/TD]
[TD]19.5[/TD]
[TD]48[/TD]
[/TR]
[TR]
[TD]11/16/2012 06:00[/TD]
[TD].022[/TD]
[TD]16.7[/TD]
[TD].3[/TD]
[TD]1[/TD]
[TD]19.2[/TD]
[TD]47[/TD]
[/TR]
[TR]
[TD]11/16/2012 07:00[/TD]
[TD].025[/TD]
[TD]16.5[/TD]
[TD].3[/TD]
[TD]351[/TD]
[TD]18.9[/TD]
[TD]48[/TD]
[/TR]
[TR]
[TD]11/16/2012 08:00[/TD]
[TD].021[/TD]
[TD]16.6[/TD]
[TD].3[/TD]
[TD]357[/TD]
[TD]18.7[/TD]
[TD]47[/TD]
[/TR]
[TR]
[TD]11/16/2012 09:00[/TD]
[TD].025[/TD]
[TD]16.7[/TD]
[TD].3[/TD]
[TD]358[/TD]
[TD]18.5[/TD]
[TD]47[/TD]
[/TR]
</tbody>[/TABLE]