diff --git a/app.js b/app.js
index ad9a93a7..f6652126 100644
--- a/app.js
+++ b/app.js
@@ -1 +1,55 @@
 '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 prefactureDataMap = 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 prefacture = columns[1];
+    const popu = parseInt(columns[3]);
+   
+    if(year === 2010 || year === 2015) {
+      let value = prefactureDataMap.get(prefacture);
+      if (!value) {
+        value = {
+          popu10: 0,
+          popu15: 0,
+          change: null
+      };
+    }
+    if (year === 2010){
+      value.popu10 = popu;
+    }
+    if (year === 2015){
+      value.popu15 = popu;
+    }
+    prefactureDataMap.set(prefacture,value);
+    }
+});
+rl.on('close',() => {
+    for (let [key,value] of prefactureDataMap) {
+      value.change = value.popu15 / value.popu10;
+    }
+
+    const rankingArray = Array.from(prefactureDataMap).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