Cannot get information about commit count and repository size using GraphQL

I'm using the graphql explorer to get information about repositories, but... statistic always returns null. I tried with another repositories but the result is always the same.

I would like to get this information using GraphQL itself instead of request the REST API.

query makeRepoQuery {
  project(fullPath:"gitlab-org/gitlab-ce"){
    forksCount
    starCount
    openIssuesCount
    statistics {
      commitCount
      repositorySize
    }
  }
}

Returns:

{
  "data": {
    "project": {
      "forksCount": 5709,
      "starCount": 6143,
      "openIssuesCount": 16485,
      "statistics": null
    }
  }
}