<p>Yes, I started with “reduce the reputation”, so I'm going to be downvoted into oblivion.</p>

<p><a href="http://meta.stackexchange.com/questions/19470/do-you-ever-not-upvote-a-question-that-you-answer">Ever since the early days</a>, <a href="http://meta.stackexchange.com/questions/16896/why-dont-people-vote-up-questions-that-they-answer">it was apparent that many questions got answers but no upvotes</a>, and the general response was that answerers should upvote the questions they answer most of the time.</p>

<p>I can think of only a few reasons not to upvote a question I've answered:</p>

<ol>
<li>I've run out of votes.</li>
<li>A new user lacking the 15 rep to upvote.</li>
<li>The question is a good one, but so badly asked it doesn't deserve upvoting as is.</li>
<li>The question is technically valid, but so trite it doesn't deserve upvoting.</li>
</ol>

<p>Well, looks like the team is prepared to help with #1, by <a href="http://meta.stackexchange.com/questions/89534/separate-vote-pools-for-questions-and-answers">providing more votes for questions</a>.<br>
For #2, let's just say that new users (&lt;15rep) get a dispensation.<br>
For #3, now everyone has access to the <code>edit</code> button to improve the question.<br>
For #4, well, if the question is so trite, the answer can't be that difficult.  </p>

<p>So: if you <strong>answer a question and don't upvote it</strong>, I propose that you <strong>earn less reputation from answer votes</strong>. Perhaps only +5 rather than +10.  </p>

<p>I'm aware that this discloses whether you've voted on a question if you've answered it. I don't think this is a problem. Remember that you can vote up or down.</p>

<hr>

<p><sub> Before proposing this, I wanted to see how many people would be affected. The answer is, <strong>a lot</strong>. <em>(Hoping these queries mean what I think they mean since this is my first foray in the data explorer.)</em> </sub></p>

<ul>
<li><sup> <a href="http://data.stackexchange.com/stackoverflow/s/1317/zero-score-questions" rel="nofollow">Zero-score questions</a>: On SO, 5.5% of questions have a score of 0 and no answer. 19.4% have a score of 0 and one answer. 11.6% have a score of 0 and two answers. </sup></li>
<li><sup> <a href="http://data.stackexchange.com/stackoverflow/s/1311/question-score-distribution" rel="nofollow">Question score distribution</a>: On SO, 46% of all questions have a score of 0. About 1% have a negative score (all these queries look at score, not upvotes, but this 1% figure shows that downvotes are second-order). </sup></li>
<li><sup> <a href="http://data.stackexchange.com/stackoverflow/s/1326/score-excedent-distribution" rel="nofollow">Question upvote excedent</a>: Only 13.2% of questions have more upvotes than they have answers. 15.7% have as many. 32.3% have one less. 37.9% have at least two more answers than upvotes. <a href="http://data.stackexchange.com/stackoverflow/s/1325/question-score-against-number-of-answers-relative" rel="nofollow">More breakdown</a>. </sup></li>
<li><sup> I thought people might be refraining from upvoting questions because they were afraid of running out of votes. So here's a <a href="http://data.stackexchange.com/stackoverflow/s/1327/question-score-by-time-of-day" rel="nofollow">question vote deficit breakdown by question time</a>. So, yes, time has an effect, but it's small: if you ask between 0:00 and 1:00 UTC, and get at least one answer, you have a 31.8% chance of getting more upvotes than answers. Between 6:00 and 7:00, the chance drops to 26.8%. That's barely statistically significant. </sup></li>
</ul>