Typically a graph is meant to visually show the similarities and
differences or cycle-to-cycle changes between related groups of
figures. For instance: a graph of swimwear department sales would show
a decline in winter months and an increase in summer months. Including
the "total sales for all departments" figure in that graph skews the
scaling of the graph (as you've found out) and includes unnecessary
data in your comparison, because although swimwear dept. sales are a
part of total sales, you can't tell from the graph what part of total
sales is swimwear (unless it's a separate pie chart). My suggestion
is: remove "total sales all departments" from the departmental graphs
and include a summary graph showing total sales for 2004 2005 2006.