remove unknown variable

src/index.js

@@ -233,10 +233,10 @@ async function agregateMonthAndYearData(data) {
 
     data.forEach(element => {
       element.year + '-' + element.month in monthData
-        ? (monthData[element.year + '-' + element.month] += element.load - oldValue)
+        ? (monthData[element.year + '-' + element.month] += element.load)
         : (monthData[element.year + '-' + element.month] = element.load)
       element.year in yearData
-        ? (yearData[element.year] += element.load - oldValue)
+        ? (yearData[element.year] += element.load)
         : (yearData[element.year] = element.load)
     })
     // Agregation for Month data