Calculate Prior Year Values

Anonymous , Try using

dax
UOM_Selected_Year =
CALCULATE(
SELECTEDVALUE(financial[UOM %]),
FILTER(dim_time, dim_time[year] = SELECTEDVALUE(dim_time[year]) &&
(dim_time[period] = "FY" || dim_time[period] = "H1")),
FILTER(dim_region, dim_region[region_name] = "Global")
)

UOM_Prior_Year =
VAR SelectedYear = SELECTEDVALUE(dim_time[year])
VAR PriorYear = SelectedYear - 1

RETURN CALCULATE(
SELECTEDVALUE(financial[UOM %]),
FILTER(dim_time, dim_time[year] = PriorYear &&
(dim_time[period] = "FY" || dim_time[period] = "H1")),
FILTER(dim_region, dim_region[region_name] = "Global")
)

UOM_difference =
VAR UOM_Selected_Year_Value = [UOM_Selected_Year]
VAR UOM_Prior_Year_Value = [UOM_Prior_Year]

RETURN IF(
NOT ISBLANK(UOM_Selected_Year_Value) && NOT ISBLANK(UOM_Prior_Year_Value),
DIVIDE(UOM_Selected_Year_Value - UOM_Prior_Year_Value, UOM_Prior_Year_Value) * 100,
BLANK()
)