Average Listening Sessions per Listener

Problem

Table: `Plays`

```text
+--------------+---------+
| Column | Type |
+--------------+---------+
| listener_id | int |
| session_ref | int |
| play_day | date |
| track_genre | varchar |
+--------------+---------+
There is no single-column primary key. Each row is one track play inside a
listening session.
```

For the 30-day window ending **2024-09-30 inclusive** (from 2024-09-01 to
2024-09-30), return the average number of distinct sessions per distinct
listener, rounded to 2 decimal places. If there are no rows in the window the
answer should be 0.00. Use the column heading `avg_sessions_per_listener`.

**Example**

```text
Plays:
+-------------+-------------+------------+-------------+
| listener_id | session_ref | play_day | track_genre |
+-------------+-------------+------------+-------------+
| 1 | 100 | 2024-09-01 | jazz |
| 1 | 100 | 2024-09-01 | jazz |
| 1 | 101 | 2024-09-02 | rock |
| 2 | 200 | 2024-09-10 | pop |
+-------------+-------------+------------+-------------+

Output:
+---------------------------+
| avg_sessions_per_listener |
+---------------------------+
| 1.5 |
+---------------------------+
```

There are 3 distinct sessions (100, 101, 200) across 2 distinct listeners, so
3 / 2 = 1.5.

Tables

Example rows — the live problem includes the full dataset.

Expected output

Your answer should return 1 row with the columns avg_sessions_per_listener.

Starter code (SQL)

SELECT *
FROM Plays;

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