| Table 2. Estimated stock numbers. | ||||||
| Year\Age | 0 | 1 | 2 | 3 | 4 | 5+ |
| 1991 | 100007 | 138968 | 110084 | 33423 | 3048 | 11136 |
| 1992 | 40660 | 62380 | 75584 | 54394 | 13014 | 7036 |
| 1993 | 91675 | 25413 | 33725 | 36134 | 20921 | 10058 |
| 1994 | 135537 | 56500 | 13870 | 16141 | 13216 | 14602 |
| 1995 | 152512 | 82125 | 29437 | 6720 | 5869 | 12776 |
| 1996 | 106298 | 92319 | 41028 | 13423 | 2515 | 8550 |
| 1997 | 88965 | 64344 | 45026 | 18439 | 4917 | 5216 |
| 1998 | 67982 | 52892 | 32112 | 19386 | 6372 | 5073 |
| 1999 | 151146 | 40215 | 26134 | 13924 | 6556 | 5792 |
| 2000 | 133920 | 92967 | 19518 | 10973 | 4702 | 6186 |
| 2001 | 351864 | 83034 | 43652 | 7735 | 3798 | 5677 |
| 2002 | 484077 | 228433 | 38638 | 16722 | 2675 | 4960 |
| 2003 | 514011 | 319976 | 111302 | 15478 | 6085 | 4194 |
| 2004 | 220577 | 348363 | 161619 | 46864 | 5979 | 6055 |
| 2005 | 230729 | 150995 | 182956 | 69286 | 19766 | 6809 |
| 2006 | 230268 | 161781 | 82785 | 79618 | 30242 | 15375 |
| 2007 | 252206 | 160492 | 87378 | 37949 | 34166 | 25261 |
| 2008 | 284077 | 173859 | 85306 | 40215 | 17396 | 31351 |
| 2009 | 415817 | 197600 | 89232 | 40215 | 19113 | 26903 |
| 2010 | 519696 | 290686 | 99409 | 41982 | 19718 | 27011 |
| 2011 | 660003 | 369535 | 147414 | 47193 | 20723 | 29231 |
| 2012 | 398714 | 470711 | 193107 | 73057 | 23553 | 32958 |
| 2013 | 871525 | 288082 | 250196 | 97734 | 37835 | 38025 |
| 2014 | 447307 | 648229 | 159532 | 127134 | 51586 | 51175 |
| 2015 | 449100 | 326766 | 364397 | 81879 | 66636 | 68186 |