24 years ago:

"The Taxpayers Relief Act of 1997 (TRA97) has generated the largest changes in the tax treatment of housing capital gains since the late 1970s, and therefore, serves as a natural experiment for researchers to study the impact of capital gains taxation on housing markets.

Prior to TRA97, homeowners had to pay capital gains taxes when they sold their homes unless they resorted to the “roll-over rule” or the “age-55 rule.” The roll-over rule allowed a home seller to postpone his capital gains provided that he bought another home of equal or greater value within two years. The age-55 rule allowed home sellers of age 55 or older to claim a one-time exclusion of $125,000 against their capital gains."

Which is why asking a program user community about a tax rule, which the program in use is for taxes, really isn't the best resource for someone who should know this stuff and stay current on it. Remember, the IRS is your tax dollars at work; they put on the web the resources you need, because you already paid them to do that part.