How much do you need to retire? – [Money Central] Most retirees will also receive Social Security benefits that could replace another 20% or 30% of pre-retirement income. For the average wage earner — with an income of $37,000 in 2005 — Social Security replaces about 42% of pre-retirement income; the figure is less for those with higher earnings. That would boost total income close to the 75% to 85% range of pre-retirement earnings generally recommended…