page.rb seaches for divs that are not in the current HTML of factbook such as:
[ @opts[:fields] ? 'Introduction' : 'intro', '<div id="CollapsiblePanel1_Intro"' ],
[ @opts[:fields] ? 'Geography' : 'geo', '<div id="CollapsiblePanel1_Geo"' ],
[ @opts[:fields] ? 'People and Society' : 'people', '<div id="CollapsiblePanel1_People"' ],
[ @opts[:fields] ? 'Government' : 'govt', '<div id="CollapsiblePanel1_Govt"' ],
[ @opts[:fields] ? 'Economy' : 'econ', '<div id="CollapsiblePanel1_Econ"' ],
[ @opts[:fields] ? 'Energy' : 'energy', '<div id="CollapsiblePanel1_Energy"' ],
[ @opts[:fields] ? 'Communications' : 'comm', '<div id="CollapsiblePanel1_Comm"' ],
[ @opts[:fields] ? 'Transportation' : 'trans', '<div id="CollapsiblePanel1_Trans"' ],
[ @opts[:fields] ? 'Military' : 'military', '<div id="CollapsiblePanel1_Military"'],
[ @opts[:fields] ? 'Transnational Issues': 'issues', '<div id="CollapsiblePanel1_Issues"' ]
So the resulting data is always empty.