Using over a million real-time reports from a large U.S. sample group, a recent study found that happiness increases linearly with reported income (logarithmic), and continues to rise beyond the $80,000/year mark.
As someone earns more, they may have the ability to purchase things that reduce suffering. This is particularly true when comparing low to moderate income groups—larger incomes below $80,000/year still showed a strong association with reduced negative feelings.