diff --git a/app.js b/app.js
index ad9a93a7..6156b9a4 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 prefectureDataMap = new Map(); // key: 都道府県 value: 集計データのオブジェクト
+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 = prefectureDataMap.get(prefecture);
+        if (!value) {
+            value = {
+                popu10: 0,
+                popu15: 0,
+                change: null
+            };
+        }
+        if (year === 2010) {
+            value.popu10 = popu;
+        }
+        if (year === 2015) {
+            value.popu15 = popu;
+        }
+        prefectureDataMap.set(prefecture, value);
+    }
+});
+rl.on('close', () => {
+    for (let [key,value] of prefectureDataMap) {
+        value.change = value.popu15 / value.popu10;
+    }
+    const rankingArray = Array.from(prefectureDataMap).sort((pair1, pair2) => {
+        return pair1[1].change - pair2[1].change;
+    });
+    const rankingStrings = rankingArray.map(([key, value], i) => {
+        return (
+            (i + 1) +
+            '位 ' +
+            key +
+            ': ' +
+            value.popu10 +
+            '=>' +
+            value.popu15 +
+            ' 変化率:' +
+            value.change
+        );
+    });
+    console.log(rankingStrings);
+});