Grouping barplot, y axis in percent

[<Patrick.Heer@bakom.admin.ch>]

Dear all
Using S-Plus 6.0 for Windows XP

I am using a dataframe with numerous factor variables.
I'd like to plot, for example, a grouping barplot showing variable Sex
(2 categories) in percent for each Age (6 categories).

The data look the following way:

Sex     Age
Man     0-20
Woman   21-30
Man     21-30
Man     65+
...

PS: I tried to use the cross tab function, but it is veray expensive in
coding

Thanks in advance
Patrick