add support for network calculation from the calculator

lib/components/pages/stats.dart

@@ -170,6 +170,21 @@ class _StatsPageState extends State<StatsPage> {
                   ),
                 ),
               ),
+            if (year.topCountries.isNotEmpty)
+              _buildSection<StatsCountryMileage>(
+                context,
+                title: 'Top countries',
+                items: year.topCountries,
+                emptyLabel: 'No country data',
+                itemBuilder: (item, index) => ListTile(
+                  dense: true,
+                  contentPadding: const EdgeInsets.symmetric(horizontal: 8),
+                  title: Text(item.country),
+                  trailing: Text(
+                    distanceUnits.format(item.mileage, decimals: 1),
+                  ),
+                ),
+              ),
             _buildSection<StatsStationVisits>(
               context,
               title: 'Top stations',