Well, it really depends on what class your character is, because the classes have different minimums for different traits, and some have higher minimums than others. A Paladin or Ranger for example, would get a fairly high die roll on a good try. For Generally, anywhere in the 80's is pretty good, 90's would take you a lot longer time, although there are those who roll for hours to get that 95
.
Just remember to distribute your roll accordingly for your class and don't do something like give your mage an intelligence of 9, but a strength of 15
.