>NA</span>, ylab <span class="op">=</span> <span class="cn">NA</span>, </span>
<span>     sub <span class="op">=</span> <span class="st">"The smoothed level with 90% confidence intervals, </span></span>
<span><span class="st">            and the observed data points"</span><span class="op">)</span></span>
<span><span class="fu"><a href="https://rdrr.io/r/graphics/lines.html" class="external-link">lines</a></span><span class="op">(</span><span class="fl">1871</span><span class="op">:</span><span class="fl">1