Here's the same table sorted by hours for easier reading:

  hours  count  percent
  0-4     7     3
  5-20   14     5
  20-30  11     4
  30-40  42     16
  40-50  66     25
  50-60  52     20
  60-70  35     13
  70-80  16     6
  80+    21     8