Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
How many entries are shown for date of successors formal installation where successor is john w. walker (dr)?

### Inputs:
table_name: table, columns: ['State (class)', 'Vacator', 'Reason for change', 'Successor', 'Date of successors formal installation']

### Response:
SELECT COUNT Date of successors formal installation FROM table WHERE Successor = John W. Walker (DR)