Почему double, а не decimal?

ring _query = "SELECT HistoryId, Money, Paper FROM {0} WHERE Date = (SELECT MAX(DATE) FROM {0} )";
_query = String.Format(_query, sqlTableName);
SqlCommand _sqlCommand = new SqlCommand(_query, _sqlConn);

using (SqlDataReader _dataReader = _sqlCommand.ExecuteReader())
    while (_dataReader.Read())
    {
        HistoryId = _dataReader.GetInt64(0);
        Money = _dataReader.GetDecimal(1);
        Paper = _dataReader.GetInt32(2);
    }

A first chance exception of type 'System.DivideByZeroException' occurred in mscorlib.dll
System.Transactions Critical: 0 : <TraceRecord xmlns="http://schemas.microsoft.com/2004/10/E2ETraceEvent/TraceRecord" Severity="Critical"><TraceIdentifier>http://msdn.microsoft.com/TraceCodes/System/ActivityTracing/2004/07/Reliability/Exception/Unhandled</TraceIdentifier><Description>Unhandled exception</Description><AppDomain>Mts.vshost.exe</AppDomain><Exception><ExceptionType>System.DivideByZeroException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</ExceptionType><Message>Attempted to divide by zero.</Message><StackTrace> at System.Decimal.FCallDivide(Decimal&amp;amp; d1, Decimal&amp;amp; d2)
at System.Decimal.op_Division(Decimal d1, Decimal d2)
at Goricap.Mts.BuySell.&amp;lt;initProfitTimer&amp;gt;b__c(Object data) in G:\C\Development\MTS_Decimal\Programm\BuySellClass.cs:line 333
at System.Threading._TimerCallback.TimerCallback_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
at System.Threading._TimerCallback.PerformTimerCallback(Object state)</StackTrace><ExceptionString>System.DivideByZeroException: Attempted to divide by zero.
at System.Decimal.FCallDivide(Decimal&amp;amp; d1, Decimal&amp;amp; d2)
at System.Decimal.op_Division(Decimal d1, Decimal d2)
at Goricap.Mts.BuySell.&amp;lt;initProfitTimer&amp;gt;b__c(Object data) in G:\C\Development\MTS_Decimal\Programm\BuySellClass.cs:line 333
at System.Threading._TimerCallback.TimerCallback_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
at System.Threading._TimerCallback.PerformTimerCallback(Object state)</ExceptionString></Exception></TraceRecord>