average price fact table

Hello,

I'm designing a fact table for average prices on a transport route. Below is an example of the xml data that we need to model.
I'm having trouble Identifying the grain here. Would it be seat type per price range per customer ? So in the example of FirstClass would the grain be 1 line per combination giving a total of 177 rows in fact table (1 seat * 59 dates * 3 customers)

Any other ideas on how to model this?

Many thanks

Code:

<Route Type="OneWay" Vehicle="Bus" From="abc" To="abc">
<Seat Type="FirstClass">
<Prices>
<Price DateStart="20150101" DateTo="20150131" Price="10" Customer="All"/>
<Price DateStart="20150201" DateTo="20150228" Price="11" Customer="All"/>
</Prices>
</Seat>
<Seat Type="Economy">
<Prices>
<Price DateStart="20150101" DateTo="20150131" Price="5"  Customer="All"/>
<Price DateStart="20150201" DateTo="20150228" Price="7" Customer="All"/>
<Price DateStart="20150201" DateTo="20150228" Price="6" Customer="c"/>
</Prices>
</Seat>
<Customers>
<Customer Name="a"/>
<Customer Name="b"/>
<Customer Name="c"/>
</Customers>
</Route>

What does the XML data represent? A price list or a list of customers and the price they paid?

You would need the latter to calculate an average seat price.

the xml is a selling contract per transport route, so basically represents how much a customer can sell a seat for.

questions that would need to be answered would be things like average price per day/month (well all date attributes) per customer per seat type per route type etc