| Table 2. Estimated stock numbers. | ||||
| Year\Age | 1 | 2 | 3 | 4+ |
| 1991 | 38455028 | 2082334 | 116658 | 970 |
| 1992 | 73294784 | 4412712 | 234685 | 17287 |
| 1993 | 64876758 | 10180656 | 542531 | 32533 |
| 1994 | 93642978 | 11628854 | 867178 | 51072 |
| 1995 | 66319863 | 15728737 | 1813919 | 68391 |
| 1996 | 39784980 | 7429729 | 1498537 | 165215 |
| 1997 | 63846990 | 5015281 | 625934 | 111302 |
| 1998 | 49973329 | 7174187 | 592437 | 46864 |
| 1999 | 110331497 | 6504469 | 487478 | 31793 |
| 2000 | 89343585 | 10788594 | 513497 | 29762 |
| 2001 | 43184837 | 9549506 | 956466 | 40905 |
| 2002 | 50677876 | 5101270 | 457257 | 47240 |
| 2003 | 72710765 | 4390703 | 281532 | 23506 |
| 2004 | 71987280 | 6082948 | 287794 | 9654 |
| 2005 | 97172664 | 6156383 | 319976 | 9834 |
| 2006 | 39784980 | 10334517 | 448651 | 17648 |
| 2007 | 35075029 | 4906150 | 712831 | 32080 |
| 2008 | 44633712 | 4269469 | 359331 | 45116 |
| 2009 | 109233680 | 4975319 | 411679 | 29437 |
| 2010 | 72710765 | 16970719 | 791749 | 70615 |
| 2011 | 40184825 | 8666712 | 2429024 | 151752 |