For the first 6% of Carlene's salary, her employer matches 100% of her 401(k) contributions, and from 6% to 12%, Carlene's employer matches 50% of her 401(k) contributions. Carlene's salary is $40,000, and last year, she contributed $4000 to her 401(k) plan. What was her employer's contribution to the 401(k)?​