To start, take a look at this tutorial for summary reports: Creating Filemaker Pro summary reports--Tutorial
That may not get you up and running on every detail so feel free to use Post a new Answer to ask follow up questions.
Thanks for the help on this, it's given me what I was looking for and created another question at the same time.
I've summed and grouped my values by Type, Year and Customer and this generates on a layout. I've removed the Body part as it doesn't lend itself to what I need to do. This all looks pretty good:)
What I need to do now is to get a calculation in a trailing group, not sure following some tests I've done if this can be done.
I can get a summary there, I can get two summaries there, but I can't get "Summary Value Type A - Summary Value Type B", or furthermore, a percentage calc.
So I need to keep displaying what I have, people want to see that info, and then get further calculated info alongside it or beneath it.
I hope that makes sense,
If you refer to a summary field in a calculation, you get the "grand total" value rather than the sub total that you see when you place it inside a sub summary layout part. To access the sub total for use in a calculation, use the GetSummary function--something that you can look up in FileMaker help. Make the "break field" parameter the same as your "when sorted by" field specified for the sub summary layout part. (Note: unlike sub summary parts, the break field has to be defined in the same table as the summary field.)
Great explanation - thanks. I had just started looking at that little nugget and what you've written really helped.
I'm now summarising and GETting various data groups where I need to which means I can do A/B*100 and other funky stuff.