Why does my jQuery click handler appear to run multiple times for some of its targets?

I apply:

$(".newContentLink").click(function() {
    $("#test").append("1");
});

On this:

<span id="contents">
<input class="newContentLink" type="submit" style="width: 100%;" value="CREATE A NEW CONTENT"/>
<span id="content1" class="content study">
</span>
<input class="newContentLink" type="submit" style="width: 100%;" value="CREATE A NEW CONTENT"/>
<span id="content3" class="content study">
</span>
<input class="newContentLink" type="submit" style="width: 100%;" value="CREATE A NEW CONTENT"/>
<span id="content4" class="content category">
</span>
<input class="newContentLink" type="submit" style="width: 100%;" value="CREATE A NEW CONTENT"/>
</span>

How come when I click on the first 2 buttons it adds 111, the next button adds 11, and the last one adds 1?