I was bored and did a few calculations
- So/Sp is most common for 1/6 types
- So/Sx is most common for 7/18 types
- So is more common for 5/9 types
- Sp/So is most common for 5/18 types
- Sp/Sx is most common for 1/6 types
- Sp is most common for 4/9 types
- So/Sp is least common for 0 types
- So/Sx is least common for 1/9 types
- So is least common for 1/9 types
- Sp/So is least common for 5/18 types
- Sp/Sx is least common for 1/18 types
- Sp is least common for 1/3 types
- Sx/Sp is least common for 1/9 types
- Sx/So is least common for 4/9 types
- Sx is least common for 5/9 types
PS: for the ones where you listed 2 as least likely, I counted them each as a half.