| Table 2. Estimated stock numbers. | ||||||
| Year\Age | 1 | 2 | 3 | 4 | 5 | 6+ |
| 1997 | 14915 | 6396 | 9021 | 1405 | 341 | 136 |
| 1998 | 13306 | 10762 | 2656 | 2785 | 405 | 112 |
| 1999 | 11901 | 9011 | 5965 | 680 | 594 | 112 |
| 2000 | 7771 | 8300 | 3666 | 1425 | 171 | 145 |
| 2001 | 6990 | 4248 | 2988 | 917 | 256 | 61 |
| 2002 | 11495 | 4024 | 1633 | 607 | 131 | 59 |
| 2003 | 2925 | 6375 | 1391 | 418 | 154 | 38 |
| 2004 | 16272 | 1943 | 2264 | 362 | 117 | 68 |
| 2005 | 8441 | 10212 | 568 | 733 | 96 | 54 |
| 2006 | 9401 | 5065 | 3079 | 171 | 166 | 43 |
| 2007 | 2738 | 4100 | 1108 | 615 | 52 | 81 |
| 2008 | 1431 | 955 | 658 | 202 | 152 | 34 |
| 2009 | 4257 | 589 | 186 | 125 | 49 | 24 |
| 2010 | 4215 | 2037 | 177 | 46 | 23 | 12 |
| 2011 | 5316 | 2270 | 584 | 51 | 16 | 8 |
| 2012 | 12079 | 2445 | 470 | 189 | 29 | 11 |
| 2013 | 17675 | 5847 | 960 | 252 | 67 | 21 |
| 2014 | 6001 | 10031 | 1873 | 541 | 160 | 52 |
| 2015 | 3261 | 2171 | 3338 | 1306 | 352 | 141 |
| 2016 | 322 | 1256 | 1030 | 1616 | 807 | 282 |
| 2017 | 8717 | 165 | 491 | 456 | 892 | 654 |