The 2006 economic survey also found that households in the top two income quintiles , those with an annual household income exceeding $ 60,000 , had a median of two income earners while those in the lower quintiles ( 2nd and middle quintile ) had median of only one income earner per household .
The 2005 economic survey also found that households in the top 40 % , those with an annual household income exceeding $ 55,331 , had a median of two income earners while those in the lower quintiles ( 2nd and middle quintile ) had median of only one income earner per household .