How to write DAX measure to calculate average for year

I've like t write a measure to calculate the average sales for each year;


I've tried a couple of methods, one ;

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Which give the correct answer providing all dates / months have values in them
I have also used AVERAGEX with crossjoin,

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This works but can I just use average and wrap in calculate to remove or keep filter context as required, as for the denominator in a percentage?

Workbook attached.

Richard.

Thanks, I knew I was making hard work of it, I'd tried just about every combination, using all , values, allexcept , crossjoin and summeraize.

RD