| Table 2. Estimated stock numbers. | ||||||
| Year\Age | 0 | 1 | 2 | 3 | 4 | 5+ |
| 1991 | 41564 | 64861 | 57412 | 17622 | 1382 | 2837 |
| 1992 | 13677 | 26742 | 35454 | 24294 | 5861 | 1205 |
| 1993 | 28941 | 8852 | 14580 | 14743 | 8057 | 2030 |
| 1994 | 36498 | 18550 | 4866 | 6065 | 4785 | 2788 |
| 1995 | 37798 | 23225 | 10059 | 2049 | 1975 | 2047 |
| 1996 | 25591 | 24222 | 12480 | 4112 | 682 | 1078 |
| 1997 | 20052 | 16546 | 12936 | 5075 | 1347 | 475 |
| 1998 | 13996 | 12900 | 8980 | 5151 | 1629 | 504 |
| 1999 | 34614 | 9080 | 7016 | 3645 | 1650 | 598 |
| 2000 | 28226 | 23389 | 4938 | 2834 | 1188 | 631 |
| 2001 | 97052 | 19206 | 12657 | 1952 | 934 | 527 |
| 2002 | 136899 | 68118 | 10279 | 4944 | 638 | 424 |
| 2003 | 143200 | 96568 | 37049 | 4061 | 1640 | 312 |
| 2004 | 50767 | 102437 | 52470 | 14615 | 1370 | 605 |
| 2005 | 54995 | 36644 | 56106 | 20490 | 5093 | 589 |
| 2006 | 51124 | 40296 | 20441 | 21884 | 7258 | 1731 |
| 2007 | 56162 | 37272 | 22449 | 8210 | 7769 | 2686 |
| 2008 | 64473 | 40538 | 20673 | 9037 | 3094 | 3061 |
| 2009 | 98815 | 47193 | 22382 | 8458 | 3466 | 1945 |
| 2010 | 122639 | 72548 | 26004 | 9123 | 3275 | 1828 |
| 2011 | 164062 | 91126 | 40175 | 10679 | 3533 | 1832 |
| 2012 | 91491 | 121905 | 50818 | 16884 | 4181 | 2035 |
| 2013 | 211082 | 68803 | 67778 | 21418 | 6728 | 2426 |
| 2014 | 106192 | 161781 | 38832 | 28538 | 8556 | 3619 |
| 2015 | 104820 | 79937 | 91950 | 16449 | 11307 | 4731 |