>
  <dt>	POyy	</dt><dd><p>County population for the years yy: 1960, 1970, 1980, 1990</p></dd>
  <dt>	RDyy	</dt><dd><p>Resource deprivation for the years yy: 1960, 1970, 1980, 1990 (principal component)</p></dd>
  <dt>	PSyy	</dt><dd><p>Population structure for the years yy: 1960, 1970, 1980, 1990 (principal component)</p></dd>
  <dt>	UEyy	</dt><dd><p>Unemployment rate for the years yy: 1960, 1970, 1980, 1990</p></dd>
  <dt>	DVyy	</dt><dd><p>Divorce rate for the years yy: 1960, 1970, 1980, 1990  (percentage o