Who coined the phrase The Golden Years for seniors?

Dictionary.com does not provide a word origin but notes the phrase emerged in the 1950s. Unconfirmed sources say that Merrill Lynch Investments used the phrase in an advertising campaign. The traditional golden anniversary occurs at 50 years of marriage, a mark that few couples would have seen prior to the 1950s, and golden years might bring up thoughts of people of sufficient age to have a golden anniversary, which would then imply people over about 65 or 70 years.