I have a couple of planes in a hangar, in the US. Keeping them airworthy, in the hangar, insured and ready to go ends up costing about $1000 US per month, based on experience over 10 years. Then every hour I fly costs the price of fuel above that base. That's as far as I'm interested in analyzing it... Its not a spreadsheet, its what I like to do.
I don't care what number results when you divide the annual total by the number of hours flown, and in fact I've never done it. I don't know how many hours I've flown in the last year either!