                                  &lt;NA&gt;</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 16                                  &lt;NA&gt;</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 17                                  &lt;NA&gt;</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 18                                  &lt;NA&gt;</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 19                                  &lt;NA&gt;</span>
<span class="r-out co"><