@@ 36,7 36,10 @@ public class CurrencyFigure {
     public CurrencyFigure convertTo(String resultCurrency) throws CurrencyConversionException {
         ExchangeRates rates = ExchangeRates.getExchangeOptions(new ExchangeRateKey(currency, year));
         if (rates == null) {
-            throw new CurrencyConversionException(currency, resultCurrency, year, "Could not find applicable rates data");
+            rates = ExchangeRates.getInterpolatedExchangeOptions(new ExchangeRateKey(currency, year));
+            if (rates == null) {    //if they're still null, they're very null indeed!
+                throw new CurrencyConversionException(currency, resultCurrency, year, "Could not find applicable rates data");
+            }
         }
         return rates.convertTo(resultCurrency, this, new ArrayList<>());
     }

          

@@ 90,6 90,37 @@ public class ExchangeRates {
         return exchangeRateOptions.get(key);
     }
     
+    public static ExchangeRates getInterpolatedExchangeOptions(ExchangeRateKey key) {
+        if (exchangeRateOptions.containsKey(key)) {
+            return exchangeRateOptions.get(key);
+        }
+        //Find before
+        int olderYear = key.getYear();
+        ExchangeRateKey olderKey = key;
+        do {
+            olderYear--;
+            olderKey = new ExchangeRateKey(key.getCurrency(), olderYear);
+        } while (!exchangeRateOptions.containsKey(olderKey) && olderYear > 1895);
+        
+        //Find after
+        int newerYear = key.getYear();
+        ExchangeRateKey newerKey = key;
+        do {
+            newerYear--;
+            newerKey = new ExchangeRateKey(key.getCurrency(), newerYear);
+        } while (!exchangeRateOptions.containsKey(olderKey) && newerYear < 2050);
+        
+        if (olderYear <= 1896 || newerYear >= 2050) {
+            return null;
+        }
+        
+        //If we got here, we can interpolate
+        ExchangeRates olderRates = exchangeRateOptions.get(olderKey);
+        ExchangeRates newerRates = exchangeRateOptions.get(newerKey);
+        //TODO: Interpolate
+        return olderRates;
+    }
+    
     //Gets the next level deep of conversion options.
     //E.g. we started with NOK in 1900, and got a list of options, which contains GBP, BEF, FRF, SEK, NLG, and DEM.
     //But we want USD.  So we get the next level down.

          

@@ 53,7 53,7 @@ public class Main {
     //Prior to that, it might decrease when we load EE1 cities from the DB
     static int nextXMLID = 125;
     
-    final static int[] years = { 1900, 1910, 1920, 1930 };
+    final static int[] years = { 1900, 1910, 1920, 1930, 1940 };
     
     private static DecimalFormat percentFormat = new DecimalFormat("0.00");