Comment by Hannan

It seems like there's way more on the low side than the high side, at least looking at Table 1 (below) from this PDF from the GAO:

https://www.gao.gov/assets/680/670153.pdf

Edit: below, the table contents

               Households age 55-64 with        Households age 55-64
               no retirement savings            with retirement savings


  Percent of house-        41%                        59%
  holds age 55-64

  Median net worth        $21,000                   $337,000

  Median non-retirement    $1,000                    $25,000
  financial resources

  Median income           $26,000                    $86,000

  Home ownership rates     56%                        87%  

  Percent who own a home   22%                        27%
  that is paid off

  Percent with a           32%                        45%
  defined benefit plan