| Table 2. Estimated stock numbers. | ||||||
| Year\Age | 1 | 2 | 3 | 4 | 5 | 6+ |
| 1997 | 13298 | 6651 | 10639 | 1500 | 394 | 173 |
| 1998 | 12774 | 10525 | 2602 | 2657 | 389 | 106 |
| 1999 | 11003 | 7876 | 5599 | 617 | 553 | 104 |
| 2000 | 6088 | 6532 | 3478 | 1368 | 166 | 137 |
| 2001 | 2896 | 3577 | 2662 | 896 | 243 | 58 |
| 2002 | 5881 | 2251 | 1093 | 579 | 126 | 59 |
| 2003 | 1447 | 2587 | 594 | 198 | 123 | 30 |
| 2004 | 6970 | 1381 | 1339 | 206 | 114 | 69 |
| 2005 | 3354 | 3795 | 388 | 470 | 52 | 30 |
| 2006 | 5582 | 2354 | 1790 | 144 | 110 | 30 |
| 2007 | 2080 | 1960 | 565 | 577 | 42 | 67 |
| 2008 | 742 | 393 | 308 | 110 | 103 | 23 |
| 2009 | 2076 | 195 | 63 | 74 | 41 | 19 |
| 2010 | 1443 | 1002 | 76 | 34 | 24 | 12 |
| 2011 | 1581 | 940 | 455 | 46 | 17 | 9 |
| 2012 | 3432 | 740 | 235 | 200 | 27 | 11 |
| 2013 | 3312 | 1659 | 599 | 143 | 58 | 19 |
| 2014 | 1701 | 3950 | 1320 | 607 | 141 | 14 |
| 2015 | 1174 | 914 | 3451 | 1214 | 377 | 168 |
| 2016 | 159 | 794 | 518 | 2040 | 693 | 332 |