Data values were collected and recorded about the time, in minutes, a class of second graders spent independently reading.


0 | 8 9
1 | 0 1 4 5 8
2 | 0 0 1 2 3 3 5
3 | 0 1 5 5 6
4 | 1 5
Key: 1|0 represents 10 minutes

What is the median number of minutes the second graders spent reading?
21
22
21.5
23