def proportion_of_missing_values(dfData):
    """
    Parameters
    #---------
    dfData    pandas.DataFrame containing data
    
    Returns
    #---------
    serProportions    pandas.Series containing values between 0 and 1 for each
    feature.
    
    Description
    #----------
    Computes the proportion of missing values to all values for each feature
    """
    numberOfRows = len(dfData)
    serNumberOfNans = dfData.isnull().sum()
    serProportions = serNumberOfNans/numberOfRows
    return serProportions