| Table 2. Estimated stock numbers. | ||||||
| Year\Age | 1 | 2 | 3 | 4 | 5 | 6+ |
| 1997 | 14071 | 6836 | 10150 | 1558 | 379 | 171 |
| 1998 | 13025 | 11189 | 2716 | 2733 | 392 | 109 |
| 1999 | 10491 | 8698 | 5479 | 632 | 567 | 105 |
| 2000 | 8207 | 7568 | 3498 | 1413 | 176 | 147 |
| 2001 | 4792 | 3891 | 2645 | 871 | 281 | 71 |
| 2002 | 5429 | 2532 | 1107 | 605 | 159 | 77 |
| 2003 | 3147 | 4230 | 916 | 293 | 162 | 42 |
| 2004 | 7194 | 2051 | 1929 | 335 | 156 | 106 |
| 2005 | 3583 | 3897 | 349 | 442 | 87 | 52 |
| 2006 | 4826 | 2303 | 1652 | 131 | 175 | 52 |
| 2007 | 2844 | 1932 | 524 | 581 | 70 | 112 |
| 2008 | 702 | 480 | 359 | 150 | 165 | 43 |
| 2009 | 2008 | 265 | 90 | 115 | 77 | 40 |
| 2010 | 1661 | 1479 | 102 | 50 | 53 | 30 |
| 2011 | 2529 | 1072 | 474 | 53 | 31 | 18 |
| 2012 | 3650 | 788 | 185 | 180 | 38 | 19 |
| 2013 | 4277 | 1983 | 449 | 98 | 85 | 28 |
| 2014 | 1521 | 4066 | 1054 | 298 | 62 | 50 |