Changing data series line weights in Excel chart (many at once)

Question

Is there a way to edit the weight of all lines at once on an Excel line chart?

I have a graph with about 50 data series on it, and it's too much to go through all of them and change the weights individually, and it's hard to see the data if the lines were thinner, it'd be a bit easier). I can't see a way to multi-select them, which seems a bit awful.

Edit: I eventually got it working with the following code (after learning a bit of VB). I doesn't seem to help readability of the graph much though! Chris helped me sort it out, so I'll give him the tick.

Sub onepxlines()
        With Selection
            MsgBox ("Selection: " & TypeName(Selection))
            If TypeName(Selection) = "ChartArea" Then
                Dim area As ChartArea
                Set area = Selection

                MsgBox ("Area parent: " & TypeName(area.Parent))

                If TypeName(area.Parent) = "Chart" Then
                    Dim chart As chart
                    Set chart = area.Parent
                    Dim srs As Series

                    For Each srs In chart.SeriesCollection
                        srs.Format.Line.Weight = 1.5
                    Next
                End If
            End If
        End With
End Sub

Answer 1

Probably easiest to write a quick macro, somthing like

Sub SetWeights()
    Dim srs As Series
    For Each srs In ActiveSheet.ChartObjects("Chart 1").Chart.SeriesCollection
        srs.Format.Line.Weight = 0.75
    Next
End Sub

Answer 2

I don't think you can multi-select lines. The simplest way is probably to change one and then to select each on in turn use Ctrl-Y to go through and re-do the line weight change.