Count array object values on basis of specific keys (write a function to return output of input)

write a function to return the output of the input
var input = [
{ name: 'John', age: 35, occupation: 'teacher' },
{ name: 'Jane', age: 26, occupation: 'doctor' },
{ name: 'Bob', age: 42, occupation: 'teacher' },
{ name: 'Alice', age: 29, occupation: 'engineer' },
{ name: 'Mike', age: 37, occupation: 'teacher' },
{ name: 'Lisa', age: 31, occupation: 'doctor' },
{ name: 'Steve', age: 47, occupation: 'engineer' },
{ name: 'Karen', age: 22, occupation: 'doctor' },
{ name: 'Tom', age: 25, occupation: 'teacher' },
{ name: 'Sam', age: 41, occupation: 'doctor' },
{ name: 'Hussy', age: 41, occupation: 'scientist' }
]

Output:
[
{ occupation: 'doctor', count: 4 },
{ occupation: 'teacher', count: 4 },
{ occupation: 'engineer', count: 2 }
]