How do i calculate the progress reporting of backgroundworker to a progressBar?

I have a progressBar1 in the designer. And i have a loop that i'm reporting the progress but only the user state not the int.

while (index != -1)
            {
                string firstTag = "<div class=\"CatLinkContainer\">";
                string endTag = "\" href";
                index = forums.IndexOf(firstTag, index1);

                if (index == -1)
                    continue;

                var secondIndex = forums.IndexOf(endTag, index);

                result = forums.Substring(index + firstTag.Length + 12, secondIndex - (index + firstTag.Length - 50));
                if (result.Contains("forumPage"))
                {
                    int index2 = result.IndexOf("\" href=\"http://ift.tt/1vHpBkn");
                    result = result.Remove(index2);
                    System.Threading.Thread.Sleep(1000);
                    countResults++;
                    backgroundWorker1.ReportProgress(0, result);
                    forumsNames.Add(result);
                }

                index1 = index + 1;
            }

The reporting of the result is working fine. But now i'm reporting to the progressBar1 0. I want to calculate somehow the progress and report also to the progressBar1 the percentages.

I added countResults variable int and i did countResults++;

For example in this case there are 33 result items to report the question is how do i calculate so it will get to the 100% ? In other cases could be 1 items to report or 122.

In the backgroundworker progresschanged event i did:

private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            toolStripStatusLabel1.Text = e.UserState.ToString();
            toolStripProgressBar1.Value = e.ProgressPercentage;
        }

The UserState reporting is working fine. But now how do i calculate to report the ProgressPercentage ?