><span>     xlab <span class="op">=</span> <span class="st">"Source: https://www.eia.gov/"</span>,</span></span>
<span class="r-in"><span>     ylab <span class="op">=</span> <span class="st">"Million Cubic Feet"</span><span class="op">)</span></span></span>
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<span class="r-in"><span><span class="fu"><a href="https://rdrr.io/r/graphics/mtext.html" class="external-link">mtext</a></span><span 