A new asset is available for $239,000. O&M costs are $24,000 each year for the first five years, $37,680 in year six, $57,700 in year seven, and $88,300 in year eight. Salvage values are estimated to be $198,000 after one year and will decrease at the rate of 17% per year thereafter. At a MARR of 12%, determine the economic service life of the asset. Enter your answer as an integer from 1 to 8.