Yearly average

You can do this without creating additional tables, doing it all in your measure with a virtual table.

Assuming you have a Date table with a YearMonth column for all months (including those w/o data yet), something like this should work.  This assumes you will make a visual that does not include the YearMonth column but has a filter on it limiting it to one year.  The first IF() puts a 100 in your calculation if your measure is blank for that YearMonth.  The second IF() returns a blank if Your Measure is blank for that YearMonth (i.e., not show Oct-Dec in your example).

Year Avg =
VAR summary =
    ADDCOLUMNS (
        DISTINCT ( Date[YearMonth] ),
        "@result",
            VAR result = [Your Measure]
            RETURN
                IF (
                    ISBLANK ( result ),
                    100,
                    result
                )
    )
RETURN
    IF (
        ISBLANK ( [Your Measure] ),
        BLANK (),
        AVERAGEX (
            summary,
            [@result]
        )
    )

Regards,

Pat