| Table 2. Estimated stock numbers. | ||||||
| Year\Age | 1 | 2 | 3 | 4 | 5 | 6+ |
| 1971 | 23110 | 32696 | 15098 | 4249 | 2001 | 565 |
| 1972 | 10345 | 17211 | 17824 | 6337 | 1776 | 1112 |
| 1973 | 18251 | 7827 | 9065 | 7719 | 2777 | 1390 |
| 1974 | 24760 | 15607 | 9752 | 5304 | 2494 | 1027 |
| 1975 | 23933 | 20364 | 7934 | 5128 | 1436 | 999 |
| 1976 | 12267 | 20433 | 14769 | 3157 | 1767 | 849 |
| 1977 | 23506 | 9506 | 13177 | 6595 | 876 | 879 |
| 1978 | 18894 | 22359 | 5379 | 4788 | 1678 | 472 |
| 1979 | 9540 | 15747 | 14078 | 1962 | 1727 | 599 |
| 1980 | 15987 | 7110 | 11171 | 6135 | 624 | 831 |
| 1981 | 15472 | 12817 | 4938 | 4971 | 2123 | 472 |
| 1982 | 19374 | 12539 | 6429 | 2163 | 1174 | 775 |
| 1983 | 16321 | 16604 | 7611 | 1956 | 419 | 462 |
| 1984 | 10175 | 14145 | 8670 | 2494 | 468 | 238 |
| 1985 | 7115 | 8770 | 8388 | 2753 | 591 | 160 |
| 1986 | 18564 | 5913 | 4502 | 2063 | 560 | 183 |
| 1987 | 4741 | 16212 | 3584 | 1264 | 440 | 161 |
| 1988 | 7749 | 3868 | 6173 | 1037 | 281 | 111 |
| 1989 | 3465 | 6359 | 2384 | 1951 | 263 | 115 |
| 1990 | 14003 | 2758 | 2550 | 700 | 469 | 80 |
| 1991 | 5481 | 12323 | 1341 | 589 | 147 | 113 |
| 1992 | 9791 | 4972 | 5950 | 295 | 101 | 43 |
| 1993 | 5783 | 8569 | 2674 | 2031 | 63 | 32 |
| 1994 | 7865 | 5023 | 5607 | 1154 | 598 | 24 |
| 1995 | 14612 | 6202 | 3490 | 2041 | 402 | 205 |
| 1996 | 4129 | 12088 | 3961 | 1297 | 503 | 157 |
| 1997 | 10338 | 3415 | 9313 | 1441 | 351 | 173 |
| 1998 | 8764 | 9559 | 2349 | 2802 | 368 | 120 |
| 1999 | 9140 | 6834 | 5568 | 655 | 586 | 107 |
| 2000 | 3713 | 6321 | 3623 | 1432 | 161 | 151 |
| 2001 | 2141 | 2708 | 2971 | 870 | 278 | 68 |
| 2002 | 5229 | 1909 | 1323 | 748 | 163 | 72 |
| 2003 | 1260 | 4415 | 1295 | 445 | 208 | 53 |
| 2004 | 6092 | 1053 | 2444 | 476 | 154 | 98 |
| 2005 | 2179 | 5402 | 655 | 883 | 135 | 70 |
| 2006 | 2489 | 1821 | 3110 | 243 | 263 | 68 |
| 2007 | 967 | 1437 | 892 | 878 | 79 | 116 |
| 2008 | 669 | 567 | 590 | 263 | 178 | 46 |
| 2009 | 2776 | 451 | 255 | 200 | 69 | 43 |
| 2010 | 1419 | 2471 | 283 | 92 | 56 | 30 |
| 2011 | 1543 | 1173 | 1404 | 123 | 24 | 22 |
| 2012 | 2854 | 1157 | 564 | 542 | 50 | 10 |
| 2013 | 3198 | 2243 | 670 | 185 | 161 | 19 |