Add route /population/years

src/libs/routes/population.js

@@ -25,6 +25,12 @@ populationApp.get('/year_range', (req, res, next) => {
     next();
 }, query, response('range'));
 
+populationApp.get('/years', (req, res, next) => {
+    req.sql.from('ibge_populacao').
+    field('DISTINCT ibge_populacao.ano_censo', 'years');
+    next();
+}, query, response('years'));
+
 populationApp.get('/city_size', (req, res, next) => {
     req.result = [
         {id: 1, name: "até 5000"},