How to count colored cell in datagridview?

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C#

DataGridView

I am working on access based WinForm application. I have colored cell(DateColumn) in my DataGridView. I am trying to count these cell and reflect colored cell No. on a label text. My codes are as follows:

private void metroGrid1_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
    {

        if (this.metroGrid1.Columns[e.ColumnIndex].DataPropertyName == "Date 1")
            try
            {
                var EMIDate1 = Convert.ToDateTime(metroGrid1.Rows[e.RowIndex].Cells["date1DataGridViewTextBoxColumn"].Value);


                if (EMIDate1 <= DateTime.Today)
                {
                    e.CellStyle.BackColor = Color.DarkRed;
                    e.CellStyle.ForeColor = Color.White;
                    int countDarkRed = 0;
                    for (int i = 0; i < metroGrid1.RowCount; i++)
                    {
                        if (e.CellStyle.BackColor == Color.DarkRed)
                            ++countDarkRed;
                        labelEMI.Text = "Total EMI due as on today:" + countDarkRed;
                    }
                }
            }
            catch
            {
            }
}

What I have tried:

I tried above code but these codes are counting DataGridView's rows whenever new row is added.It increases no. by 1.