Yea it has always been kinda arbitrary so I have looked at stars just as a general idea of how someone liked it. I don't always use a 0-100 score but I generally think of it as:
5 = 99 or 100
4.5 = 95-98
4 = 90-94
3.5 = 85-89
3 = 80-84
2.5 = 75-79
2 = 70-74
1.5 = 65-69
1 = 64 or below
Kind of like school grades for me, 5 star aced it, 4.5 was an A+, 4 is still an A, 3.5 B+ and so on. But that is just how I see it. But in my case, an 89 would be a 3.5, just on the cusp of an A.