| 2005 | 2006 | 2007 | 2008 | 2009 | 2010 |
---|---|---|---|---|---|---|
Non-amplified | 505 | 577 | 675 | 730 | 764 | 884 |
(83%) | (84%) | (83%) | (86%) | (87%) | (87%) | |
Amplified | 101 | 106 | 138 | 119 | 109 | 135 |
(17%) | (16%) | (17%) | (14%) | (13%) | (13%) | |
Total (n = 4843) | 606 | 683 | 813 | 849 | 873 | 1019 |
(100%) | (100%) | (100%) | (100%) | (100%) | (100%) |