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.
If you were a French or a German doctor or an engineer, would you spend 3 months fighting with the Home Office for the questionable privilege of earning £50K per annum in a country where a half decent flat costs £2500 a month?