 class="op">(</span><span class="st">'cement'</span><span class="op">)</span></span></code></pre></div>
    </div>

    <div id="format">
    <h2>Format</h2>
    <p>A data.frame with 312 observations on 30 variables:</p><ul><li><p><strong>year:</strong> 1964-1989</p></li>
<li><p><strong>month:</strong> 1-12</p></li>
<li><p><strong>prccem:</strong> BLS ppi for cement</p></li>
<li><p><strong>ipcem:</strong> industrial prod. index, cement</p></li>
<li><p><strong>prcpet:</strong> ppi for crude petroleum</p></li