Despite an improving job market and low interest rates, the share of first-time buyers fell to its lowest point in nearly three decades and is preventing a healthier housing market from reaching its full potential, according to a new survey by the National Association of Realtors.

The survey additionally found that an overwhelming majority of buyers search for homes online and then purchase their home through a real estate agent.

The 2014 National Association of Realtors Profile of Home Buyers and Sellers continues a long-running series of large national NAR surveys evaluating the demographics, preferences, motivations, plans and experiences of recent home buyers and sellers. Results are representative of owner-occupants and do not include investors or vacation homes.

The long-term average in this survey, dating back to 1981, shows that four out of 10 purchases are from first-time homebuyers. In this year’s survey, the share of first-time buyers dropped 5 percentage points from a year ago to 33 percent, representing the lowest share since 1987 (30 percent).

“Rising rents and repaying student loan debt makes saving for a down payment more difficult, especially for young adults who’ve experienced limited job prospects and flat wage growth since entering the workforce,” said Lawrence Yun, NAR’s chief economist.

The household composition of buyers responding to the survey was mostly unchanged from a year ago. Sixty-five percent of buyers were married couples, 16 percent single women, 9 percent single men and 8 percent unmarried couples.