See figure 1.3a - https://www.gov.uk/government/publications/migration-advisor...
Note that to the best of my knowledge, these numbers don't include the Afghan resettlement scheme which would further lower the proportion of employment driven visas.
Study visas do not have a pathway to settlement. Students paying through the nose for the privilege of staying for a few years to study and then leaving (or getting work visas like everyone else) is hardly a bad thing.