diff --git a/app.js b/app.js
index ad9a93a7..711630bb 100644
--- a/app.js
+++ b/app.js
@@ -1 +1,51 @@
 'use strict';
+const fs = require('fs');
+const readline = require('readline');
+const rs = fs.createReadStream('./popu-pref.csv');
+const rl = readline.createInterface({input: rs, output: {} });
+const prefectureDateMap = new Map();
+rl.on('line',lineString => {
+    const columns = lineString.split(',');
+    const year =  parseInt(columns[0]);
+    const prefecture = columns[1];
+    const popu = parseInt(columns[3]);
+
+    if (year === 2010 || year === 2015) {
+        let value = prefectureDateMap.get(prefecture);
+        if (!value){
+            value = {
+                popu10:0,
+                popu15:0,
+                change:null
+            };
+        }
+        if(year === 2010){
+              value.popu10 = popu;
+        }
+        if(year === 2015){
+              value.popu15 = popu;
+        }
+          prefectureDateMap.set(prefecture, value);
+    }
+});
+    
+    rl.on('close', ()=> {
+       for (let [key,value] of prefectureDateMap){
+           value.change = value.popu15/value.popu10;
+       }
+       const rankingArray = Array.from(prefectureDateMap).sort((pair1,pair2)=> {
+           return pair2[1].change - pair1[1].change;
+       });
+       const rankingStrings = rankingArray.map(([key, value]) => {
+           return (
+               key +
+               ': ' +
+               value.popu10 +
+               '=>' +
+               value.popu15 +
+               '　変化率:' +
+               value.change
+           );
+       });
+        console.log(rankingStrings);
+    });
\ No newline at end of file