id</span>, <span class='kw'>.t</span> <span class='kw'>=</span> <span class='no'>year</span>
  ))
<span class='co'># Note that there are still some missings - these are missings that come before the first</span>
<span class='co'># non-missing value in that unitid, so there's nothing to pull from.</span>
<span class='fu'><a href='https://rdrr.io/r/base/sum.html'>sum</a></span>(<span class='fu'><a href='https://rdrr.io/r/base/NA.html'>is.na</a></span>(<span class='no'>Scorecard</span>$<span class='no'>earning