listed origins:
```
10:24:59 swh@db1:5432=> select now(), count(*) from origin where url like 'https://repo1.maven.org/maven2/%'
swh-> ;
+------------------------------+--------+
|             now              | count  |
+------------------------------+--------+
| 2022-04-28 08:25:40.51457+00 | 186708 |
+------------------------------+--------+
(1 row)

Time: 20072.339 ms (00:20.072)
```

url present in archive:
```
10:24:31 swh-scheduler@db1:5432=> select now(), count(*) from listed_origins where visit_type='maven';
+------------------------------+---------+
|             now              |  count  |
+------------------------------+---------+
| 2022-04-28 08:24:34.35379+00 | 4048045 |
+------------------------------+---------+
(1 row)

Time: 3276.820 ms (00:03.277)
```

Which gives roughly 4.6%:
```
(* 100 (/ 186708.0 4048045.0))
```