为什么我从YQL查询中获取错误的数据？

Question

在大约一分钟内，我做了四个相同的查询。我得到了糟糕/不一致的结果。有些人丢失数据，其他人有明显不良数据。下面请注意四个音量元素。它们均来自连续查询。第一个和最后一个只返回部分数据。对于卷0返回。第二和第三卷元素似乎意味着音量下降。它应该在同一个交易日内增加。现在市场已经关闭，所以四个人都应该返回相同的数据，对吧？我已经包含了报价，然后是从四个YHOO报价中返回的数据。

<Volume>0</Volume>
<Volume>7882609</Volume>
<Volume>7310055</Volume>
<Volume>0</Volume>

https://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20yahoo.finance.quote%20where%20symbol%20in%20(%22YHOO%22%2C%22AAPL%22%2C%22GOOG%22%2C%22MSFT%22)&diagnostics=true&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys

<MyYhooQueries>
    <quote symbol="YHOO">
        <AverageDailyVolume>11189200</AverageDailyVolume>
        <Change/>
        <DaysLow/>
        <DaysHigh/>
        <YearLow>26.15</YearLow>
        <YearHigh>44.92</YearHigh>
        <MarketCapitalization>42.22B</MarketCapitalization>
        <LastTradePriceOnly>44.36</LastTradePriceOnly>
        <DaysRange/>
        <Name>Yahoo! Inc.</Name>
        <Symbol>YHOO</Symbol>
        <Volume>0</Volume>
        <StockExchange>NMS</StockExchange>
    </quote>
    <quote symbol="YHOO">
        <AverageDailyVolume>11241200</AverageDailyVolume>
        <Change>+0.01</Change>
        <DaysLow>44.03</DaysLow>
        <DaysHigh>44.72</DaysHigh>
        <YearLow>26.15</YearLow>
        <YearHigh>44.92</YearHigh>
        <MarketCapitalization>42.22B</MarketCapitalization>
        <LastTradePriceOnly>44.36</LastTradePriceOnly>
        <DaysRange>44.03 - 44.72</DaysRange>
        <Name>Yahoo! Inc.</Name>
        <Symbol>YHOO</Symbol>
        <Volume>7882609</Volume>
        <StockExchange>NMS</StockExchange>
    </quote>
    <quote symbol="YHOO">
        <AverageDailyVolume>11189200</AverageDailyVolume>
        <Change>-1.40</Change>
        <DaysLow>42.82</DaysLow>
        <DaysHigh>44.15</DaysHigh>
        <YearLow>26.15</YearLow>
        <YearHigh>44.92</YearHigh>
        <MarketCapitalization>40.89B</MarketCapitalization>
        <LastTradePriceOnly>42.96</LastTradePriceOnly>
        <DaysRange>42.82 - 44.15</DaysRange>
        <Name>Yahoo! Inc.</Name>
        <Symbol>YHOO</Symbol>
        <Volume>7310055</Volume>
        <StockExchange>NMS</StockExchange>
    </quote>
    <quote symbol="YHOO">
        <AverageDailyVolume>11189200</AverageDailyVolume>
        <Change/>
        <DaysLow/>
        <DaysHigh/>
        <YearLow>26.15</YearLow>
        <YearHigh>44.92</YearHigh>
        <MarketCapitalization>42.22B</MarketCapitalization>
        <LastTradePriceOnly>44.36</LastTradePriceOnly>
        <DaysRange/>
        <Name>Yahoo! Inc.</Name>
        <Symbol>YHOO</Symbol>
        <Volume>0</Volume>
        <StockExchange>NMS</StockExchange>
    </quote>
</MyYhooQueries>