5,378 questions per day on average over the last two weeks.

If you are interested in monitoring trends, you can use the API's /info, monitor questions_per_minute and answers_per_minute, and build some awesome graphs ;) Right now it reports:

{
  "items": [
    {
      "total_questions": 3642574,
      "total_unanswered": 735504,
      "total_accepted": 2263501,
      "total_answers": 7158925,
      "questions_per_minute": 1.69,
      "answers_per_minute": 3.31,
      "total_comments": 15457244,
      "total_votes": 22628856,
      "total_badges": 3900808,
      "badges_per_minute": 1.81,
      "total_users": 1370392,
      "new_active_users": 42,
      "api_revision": "2012.9.6.3805"
    }
  ],
  "quota_remaining": 10000,
  "quota_max": 10000,
  "backoff": 10,
  "has_more": false
}

5,378 questions per day on average over the last two weeks.

If you are interested in monitoring trends, you can use the API's /info, monitor questions_per_minute and answers_per_minute, and build some awesome graphs ;) Right now it reports:

{
  "items": [
    {
      "total_questions": 3642574,
      "total_unanswered": 735504,
      "total_accepted": 2263501,
      "total_answers": 7158925,
      "questions_per_minute": 1.69,
      "answers_per_minute": 3.31,
      "total_comments": 15457244,
      "total_votes": 22628856,
      "total_badges": 3900808,
      "badges_per_minute": 1.81,
      "total_users": 1370392,
      "new_active_users": 42,
      "api_revision": "2012.9.6.3805"
    }
  ],
  "quota_remaining": 10000,
  "quota_max": 10000,
  "backoff": 10,
  "has_more": false
}