Count ticked check boxes on form

I have a form which makes check boxes visible depending on a value selected
by the user as a start and finish value. the check boxes are split into
colums from A-C and in rows from 0-30. This works fine but what i now need to
do is count all the check boxes ticked in column A and a count of all the
check boxes ticked in column B etc..

can anyone please help me with this??

Here is the code i have used to make the check boxes visible

Dim a As Integer
Dim b As Integer
Dim c As Integer
Dim CheckA As String
Dim CheckB As String
Dim CheckC As String

StartLevel = Me.txtStartLevel.Value
FinishLevel = StartLevel + Me.txtNoOfLevels.Value - 1

For a = StartLevel To FinishLevel
CheckA = "chkLevela" & Format$(a)
Me(CheckA).Enabled = False
Me(CheckA).Visible = False
Next a

For b = StartLevel To FinishLevel
CheckB = "chkLevelb" & Format$(b)
Me(CheckB).Enabled = False
Me(CheckB).Visible = False
Next b

For c = StartLevel To FinishLevel
CheckC = "chkLevelc" & Format$(c)
Me(CheckC).Enabled = False
Me(CheckC).Visible = False
Next c