1-4 hours
14.6%  - 59 votes

5-8 hours
7.9%  - 32 votes

9-12 hours
6.4%  - 26 votes

13-16 hours
4.4%  - 18 votes

17-20 hours
5.2%  - 21 votes

21 or more hours
9.1%  - 37 votes

Never
52.3%  - 212 votes