Original: The median household income rose by 30% while the income for the 20th percentile (the lower threshold for the second lowest quintile) rose by only 28% from $14,002 to $17,984.
Simplified: For example the household income for the 80th precentile, the lower threshold for the top quintile, rose from $55,265 in 1967 to $86,867 in 2003, a 57.2% increase. The median household income rose by 30% while the income for the 20th percentile (the lower threshold for the second lowest quitile) rose by only 28% from $14,002 to $17,984.