gistfile1.php

<?php
$url = 'http://www.tepco.co.jp/forecast/html/images/juyo-j.csv';
$csv = @file($url, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
if ( !$csv ) {
  exit('error');
}
$data = array();
for($i=5,$len=count($csv); $i<$len; $i++) {
  $tmp = explode(',', $csv[$i]);
  $data[] = array(
    'date'     => str_replace('/', '-', $tmp[0]) . ' ' . $tmp[1],
    'today'    => $tmp[2],
    'yestaday' => $tmp[3],
    'used'     => ((int)$tmp[3] !== 0) ? floor((int)$tmp[2] / (int)$tmp[3] * 100) : 0,
  );
}
print_r($data);