将API数据保存到文件PHP

我正在从六个比特币交易所获得价格和交易量数据，以制作价格转换器，但它非常慢，因为每次加载页面时它都必须查询所有这些网站的数据。我想在后台运行的东西，每1分钟得到数据，并将其保存到服务器上的一个文件，然后当用户来到网站，它只是抓取它从文件与已经检索到的API数据。我一直试图使用file_put_contents无济于事。下面是我目前得到的代码:

<?php
function getData($url) {
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, $url);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
$rawData = curl_exec($curl);
curl_close($curl);
return json_decode($rawData, true);
}

//BTC Volume LocalBitcoins
$BTCVolumeLocal = getData('https://localbitcoins.com/bitcoinaverage/ticker-all-currencies/');
$LocalVolume = $BTCVolumeLocal["USD"]["volume_btc"];
//BTC Volume BTCE
$BTCVolumeBTCE = getData('https://btc-e.com/api/3/ticker/btc_usd');
$BTCEVolume = $BTCVolumeBTCE["btc_usd"]["vol_cur"];
//BTC Volume Bitstamp
$BTCVolumeStamp = getData('https://www.bitstamp.net/api/ticker/');
$StampVolume = $BTCVolumeStamp["volume"];
//BTC Volume Bitfinex
$BTCVolumeFinex = getData('https://api.bitfinex.com/v1/pubticker/btcusd');
$FinexVolume = $BTCVolumeFinex["volume"];
//BTC Volume OKCoin
$BTCVolumeOK = getData('https://www.okcoin.com/api/ticker.do?ok=1');
$OKCoinVolume = $BTCVolumeOK["ticker"]["vol"];
//BTC Volume LakeBTC
$BTCVolumeLake = getData('https://www.lakebtc.com/api_v1/ticker');
$LakeVolume = $BTCVolumeLake["USD"]["volume"];
//Totals the Volumes
$TotalVolume = $LakeVolume + $FinexVolume + $OKCoinVolume + $StampVolume + $BTCEVolume + $LocalVolume;
//Percents of Total Volume
$BTCEPercent = $BTCEVolume / $TotalVolume;
$StampPercent = $StampVolume / $TotalVolume;
$FinexPercent = $FinexVolume / $TotalVolume;
$OKPercent = $OKCoinVolume / $TotalVolume;
$LakePercent = $LakeVolume / $TotalVolume;
$LocalPercent = $LocalVolume / $TotalVolume;
//BTC Price BTCE
$BTCPriceBTCE = getData('https://btc-e.com/api/3/ticker/btc_usd');
$BTCEPrice = $BTCPriceBTCE["btc_usd"]["last"];
//BTC Price Bitstamp
$BTCPriceStamp = getData('https://www.bitstamp.net/api/ticker/');
$StampPrice = $BTCPriceStamp["last"];
//BTC Price Bitfinex
$BTCPriceFinex = getData('https://api.bitfinex.com/v1/pubticker/btcusd');
$FinexPrice = $BTCPriceFinex["last_price"];
//BTC Price OKCoin
$BTCPriceOK = getData('https://www.okcoin.com/api/ticker.do?ok=1');
$OKPrice = $BTCPriceOK["ticker"]["last"];
//BTC Price LakeBTC
$BTCPriceLake = getData('https://www.lakebtc.com/api_v1/ticker');
$LakePrice = $BTCPriceLake["USD"]["last"];
//BTC Price LocalBitcoins
$BTCPriceLocal = getData('https://localbitcoins.com/bitcoinaverage/ticker-all-currencies/');
$LocalPrice = $BTCPriceLocal["USD"]["avg_1h"];
//BTC Price * Percent
$BTCEPricePercent = $BTCEPrice * $BTCEPercent;
$StampPricePercent = $StampPrice * $StampPercent;
$FinexPricePercent = $FinexPrice * $FinexPercent;
$OKPricePercent = $OKPrice * $OKPercent;
$LakePricePercent = $LakePrice * $LakePercent;
$LocalPricePercent = $LocalPrice * $LocalPercent;
//Bitcoin Price
$bitcoinPrice = round($LakePricePercent + $OKPricePercent + $FinexPricePercent + $StampPricePercent + $BTCEPricePercent + $LocalPricePercent, 2);
?>