So something like should do the trick
=SWITCH
(
LAST(Fields.Value.Value "DataSetName") = 0, "White",
FIRST(Fields!Value.Value "DataSetName) >= LAST(Fields!Value.Value "DataSetName"), "Green",
(FIRST(Fields!Value.Value "DataSetName) / LAST(Fields!Value.Value "DataSetName")) >= 0.7, "Yellow",
(FIRST(Fields!Value.Value "DataSetName) / LAST(Fields!Value.Value "DataSetName")) < 0.7, "Red"
)
Would need to ensure that the table is ordered so that Allocation is the first value and Value Planned is the last value.