plot a graph and show the dependence of the operation execution time

I am folding the matrix in parallel and performing some function on the new matrix. I need to plot a graph and look at the execution time of a function with a different amount of thread.

my loop look that:

    for (int i = 0; i < 8; i++)
    {
        Stopwatch sw = new Stopwatch();
        var matrix3 = matrix1;
        sw.Start();
        LilMultithreading.SumAndOperationParallel(ref matrix1, matrix2, LilMultithreading.Operation, i + 1);
        sw.Stop();
        Console.WriteLine(sw.ElapsedMilliseconds);
        // masLong[i] = sw.ElapsedMilliseconds;
       // chart1.Series[0].Points.AddXY(i + 1, sw.ElapsedTicks);

        sw.Reset();
    }

I use for show graphics that code:

 chart1.Series[0].Points.AddXY(i + 1, sw.ElapsedTicks);

but chart show me not true graphics(not true numbers)