pan></span></span>
<span class="r-in"><span><span class="va">bn2</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/merge.html" class="external-link">merge</a></span><span class="op">(</span><span class="va">bn</span>,</span></span>
<span class="r-in"><span>             <span class="fu"><a href="https://rdrr.io/r/base/expand.grid.html" class="external-link">expand.grid</a></span><span class="op">(</span>year <span class="op">=</span> <span class="fu"><a href="https://rdrr.