The 1915-P Lincoln cent is one of the most difficult wheat Lincoln cents to find in Red Uncirculated grades that were struck at the Philadelphia Mint. Only the 1914-P is tougher than the 1915-P in Red Uncirculated grades from all Philadelphia struck wheat Lincoln cents.
MS60 - MS64 Red: In MS60 to MS64 Red there are many examples available. Most Uncirculated Red examples fall somewhere in this grade range.
MS65 Red: In MS65 Red they are scarce but yet still obtainable. There are possibly a couple hundred examples that survive in MS65 Red .
MS66 Red: In MS66 Red it is considered very scarce with only about 80 - 85 examples in this grade available.
MS67Red: In MS67 Red it is considered truly scarce with only 5 or so examples known to exist.
MS68 Red: In MS68 it is considered rare since there is only one coin known in the grade of MS68 Red.