b21-2"><a href="get-started.html#cb21-2" tabindex="-1"></a>  <span class="do">## add column with relative shares per year</span></span>
<span id="cb21-3"><a href="get-started.html#cb21-3" tabindex="-1"></a>  <span class="fu">group_by</span>(year) <span class="sc">|&gt;</span> </span>
<span id="cb21-4"><a href="get-started.html#cb21-4" tabindex="-1"></a>  <span class="fu">mutate</span>(<span class="at">share_year =</span> count <span class="sc">/</span> <span class="fu">sum</span>(count)) <span class="sc">|&