| Table 2. Estimated stock numbers. | ||||||
| Year\Age | 1 | 2 | 3 | 4 | 5 | 6+ |
| 1997 | 13421 | 5712 | 8517 | 1353 | 316 | 127 |
| 1998 | 11922 | 9824 | 2505 | 2554 | 362 | 105 |
| 1999 | 10625 | 7959 | 5250 | 643 | 545 | 100 |
| 2000 | 6114 | 7390 | 3336 | 1320 | 152 | 135 |
| 2001 | 4316 | 3646 | 2690 | 788 | 242 | 55 |
| 2002 | 7924 | 2963 | 1329 | 543 | 115 | 50 |
| 2003 | 1351 | 4280 | 904 | 274 | 108 | 27 |
| 2004 | 8216 | 1103 | 1454 | 232 | 79 | 45 |
| 2005 | 3015 | 3892 | 214 | 270 | 36 | 20 |
| 2006 | 3983 | 1815 | 1125 | 62 | 66 | 16 |
| 2007 | 1088 | 1717 | 446 | 246 | 21 | 31 |
| 2008 | 429 | 287 | 191 | 61 | 40 | 9 |
| 2009 | 1287 | 152 | 42 | 31 | 10 | 6 |
| 2010 | 988 | 566 | 41 | 11 | 5 | 3 |
| 2011 | 1097 | 512 | 143 | 10 | 3 | 2 |
| 2012 | 2131 | 442 | 84 | 35 | 4 | 2 |
| 2013 | 2554 | 951 | 151 | 39 | 12 | 3 |
| 2014 | 908 | 1471 | 309 | 83 | 23 | 9 |
| 2015 | 720 | 370 | 495 | 190 | 52 | 21 |
| 2016 | 186 | 262 | 158 | 193 | 94 | 37 |
| 2017 | 1355 | 137 | 116 | 61 | 65 | 38 |
| 2018 | 133 | 411 | 26 | 37 | 22 | 30 |
| 2019 | 272 | 63 | 67 | 7 | 8 | 5 |
| 2020 | 577 | 141 | 7 | 13 | 1 | 2 |
| 2021 | 237 | 186 | 20 | 1 | 3 | 0 |
| 2022 | 294 | 126 | 36 | 5 | 0 | 1 |