Find Mutations Frequencies by Cancer Type
There is one paper called "Mutational heterogeneity in cancer and the search for new cancer-associated genes" from the "The cancer genome atlas" which should be interesting for you. This project aims to map the mutations occurring in different cancers, one of the results is this figure (from reference 1):



The project itself has numerous data on the different cancers available on the project website, which can be found in reference 2.

References:


Mutational heterogeneity in cancer and the search for new
cancer-associated genes
The cancer genome atlas project website