By Tyler Newton, Partner & Director of Research at Catalyst InvestorsGrowth private equity firm Catalyst Investors issued a research report documenting historical drivers in the drop of traditional media. As reported on by Forbes.com, from 1976 to 2000, a boom in consumer spending touched off an explosive demand for new advertising inventory. That produced an overwhelming supply, "…making the 1980s the heyday of media fortunes." Cable programmers rolled out new shows and channels; magazines expanded their page counts. Later, the ad boom helped build the Web itself. "Now we have a nearly unlimited supply of potential advertising inventory," says the report.Spending as a percentage of gross domestic product declined in the years that followed (2000 to 2007)--Catalyst blames the Internet. Its unlimited content and ability to measure ad impact broke "the oligopolistic pricing power that traditional media enjoyed in the 1980s and 1990s." A further dip in ad spending as a percent of GDP will occur over the next two to three years, predicts Catalyst.