Mike operates a fishing outfitter as an accrual$-$method sole proprietorship. On March $1$st of this year, Mike received $$19,500$ for four outfitting trips. This is the first time Mike agreed to such a payment and he is obligated to outfit one trip per year for the next four summers, beginning this year. How much income must Mike recognize in each of the next four years if he is attempting to minimize his tax burden?