You are given a backlog snapshot table and asked to identify the top drivers of backlog growth over time. Write a PostgreSQL query that measures month-over-month backlog change for each queue, ranks queues within each month by their contribution to growth, and returns the ranked results in chronological order.
| Column | Type | Description |
|---|---|---|
| snapshot_date | DATE | Date the backlog snapshot was recorded |
| queue_name | VARCHAR(100) | Queue or workstream name |
| backlog_count | INT | Open backlog items at the snapshot date |
| region | VARCHAR(50) | Region associated with the queue |