If a return to the gold standard is a "core" idea which Republican's are required to advocate, 20% may be generous. Withdrawl from the UN probably drops under 20% as well.
To me, the most important "core" value would involve a candidate elucidating his values and ideas to voters, then sticking to them. R's don't need to be held to a shopping list of "values" as do the dems.
If you insist on being rational it will only serve to confuse me! ;-)