private void preloadCountryHistory() {
        GenericObject hist;
        String tag;
        
        final GenericObject countries =
                EUGFileIO.load(resolver.resolveFilename("common/countries.txt"), settings);
        
        for (ObjectVariable def : countries.values) {
            tag = def.varname;
            
            hist = historyCache.get(tag);
            if (hist == null) {
                String histFile = resolver.getCountryHistoryFile(tag);
                
                if (histFile == null) {
//                    System.err.println("Cannot find country history file for " + tag);
                    continue;
                }
                
                hist = EUGFileIO.load(histFile, settings);
                
                if (hist == null) {
                    System.err.println("Failed to load country history file for " + tag);
                } else {
                    historyCache.put(tag, hist);
                }
            }
        }
    }