| Table 2. Estimated stock numbers. | ||||||
| Year\Age | 1 | 2 | 3 | 4 | 5 | 6+ |
| 1997 | 13754 | 6825 | 10904 | 1512 | 387 | 172 |
| 1998 | 11719 | 11170 | 2705 | 2711 | 384 | 107 |
| 1999 | 9804 | 7958 | 5633 | 620 | 551 | 103 |
| 2000 | 6836 | 6849 | 3532 | 1370 | 164 | 136 |
| 2001 | 3776 | 3586 | 2632 | 871 | 243 | 59 |
| 2002 | 6169 | 2354 | 1121 | 565 | 125 | 58 |
| 2003 | 2771 | 3997 | 927 | 293 | 112 | 27 |
| 2004 | 7403 | 2008 | 1974 | 316 | 104 | 64 |
| 2005 | 3505 | 3633 | 354 | 437 | 56 | 31 |
| 2006 | 5062 | 2260 | 1714 | 131 | 119 | 33 |
| 2007 | 2529 | 1763 | 531 | 469 | 45 | 70 |
| 2008 | 869 | 450 | 340 | 118 | 99 | 24 |
| 2009 | 2347 | 247 | 83 | 93 | 39 | 19 |
| 2010 | 1679 | 1330 | 95 | 43 | 23 | 12 |
| 2011 | 1606 | 1024 | 528 | 54 | 18 | 9 |
| 2012 | 3252 | 709 | 237 | 203 | 30 | 12 |
| 2013 | 3320 | 1926 | 708 | 178 | 59 | 19 |
| 2014 | 2069 | 3476 | 1507 | 664 | 144 | 16 |
| 2015 | 3000 | 1067 | 2312 | 970 | 433 | 143 |