Bigham Corporation, an accrual basis calendar year taxpayer, sells its services under 12-month and 24-month contracts. The corporation provides services to each customer every month. On July 1, 2017, Bigham sold the following customer contracts:

Length of contract	Total Proceeds
12 months	$18,400
24 months	$36,800

Determine the income to be recognized in taxable income in 2017 and 2018.

Length of Contract	2017 Income	2018 Income
12 months	$	$
24 months	$	$