which colours to choose for progress bar values

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C#

C#4.0

In windows form,
I am using a combobox (cboProgress) and a ProgressBar (prgProgress)
In the selectedindexchanged event of the combobox (which is populated with numbers from 10 to 100 at interval of 10), I would like to set the value of the progressbar to the selected value of the combobox. And fill the forecolor of the progressbar with a different colour according to the selected number in the combobox.

Question:
Can you please give suggestions on the colours to use for filling the forecolor of the progress bar based on the selected value in the combobox?
This is what I have but I need help in setting the colours please.
Any suggestions on the colours please?

Thanks

private void cboProgress_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (cboProgress.SelectedIndex > 0)
            {
                switch (int.Parse(cboProgress.Text))
                {
                    case 10:
                        prgProgress.ForeColor = Color.?;
                        break;
                    case 20:
                        prgProgress.ForeColor = Color.?;
                        break;
                    case 30:
                        prgProgress.ForeColor = Color.?;
                        break;
                    case 40:
                        prgProgress.ForeColor = Color.?;
                        break;
                    case 50:
                        prgProgress.ForeColor = Color.?;
                        break;
                    case 60:
                        prgProgress.ForeColor = Color.?;
                        break;
                    case 70:
                        prgProgress.ForeColor = Color.?;
                        break;
                    case 80:
                        prgProgress.ForeColor = Color.?;
                        break;
                    case 90:
                        prgProgress.ForeColor = Color.?;
                        break;
                    case 100:
                        prgProgress.ForeColor = Color.DarkGreen;
                        break;
                }
                prgProgress.Value = int.Parse(cboProgress.Text);
            }
        }