The 1973 Uncirculated Kennedy Half Dollar has the lowest mintage from 1965 to 1976 for the circulation strike issues. The 1973 Half Dollar came well struck and finding examples up to about MS65 condition is very easy. MS66 examples become much more difficult but with enough searching one can be found in Uncirculated Rolls or Mint Sets. Examples in MS67 condition are very hard to find and it is probably much easier to buy one that has already been graded. Anything grading higher than MS67 is considered rare.