curl --request GET \
  --url https://api.exec.com/rest/v1/skills/{skill_id}/proficiency \
  --header 'Authorization: Bearer <token>'

{
  "data": [
    {
      "user": {
        "id": "u1a2b3c4d5e6",
        "email": "[email protected]",
        "first_name": "Jane",
        "last_name": "Smith"
      },
      "score": 82,
      "tier": "proficient",
      "observation_count": 14,
      "last_practiced_at": "2026-03-12T10:00:00Z"
    },
    {
      "user": {
        "id": "u7v8w9x0y1z2",
        "email": "[email protected]",
        "first_name": "Bob",
        "last_name": "Jones"
      },
      "score": null,
      "tier": "insufficient_data",
      "observation_count": 2,
      "last_practiced_at": "2026-03-10T15:30:00Z"
    }
  ],
  "pagination": {
    "page": 1,
    "page_size": 50,
    "total_count": 2,
    "total_pages": 1
  }
}