Excel

using (BackgroundWorker bw = new BackgroundWorker())
{
    bw.WorkerReportsProgress = true;
    bw.DoWork += ((s, e) =>
    {
        BackgroundWorker worker = s as BackgroundWorker;
        var export = e.Argument as string;
        var wapp = new Microsoft.Office.Interop.Excel.Application();
        var workbook = wapp.Workbooks.Open(@"c:\temp\nothing.xlsx");
        for (int i = 0; i < 20; i++)
        {
            worker.ReportProgress(i);
            Thread.Sleep(100);
        }

    });

    bw.ProgressChanged += ((s, e) =>
    {
        progressBar.Value = e.ProgressPercentage;
    });
    bw.RunWorkerAsync("class");
}