| Table 2. Estimated stock numbers. | |||||||
| Year\Age | 2 | 3 | 4 | 5 | 6 | 7 | 8+ |
| 1966 | 402721 | 232582 | 69633 | 22292 | 4433 | 1780 | 169 |
| 1967 | 372503 | 284646 | 96664 | 25591 | 7234 | 1192 | 529 |
| 1968 | 340442 | 259108 | 113210 | 34098 | 7802 | 982 | 226 |
| 1969 | 292436 | 236807 | 104715 | 36279 | 8760 | 2160 | 335 |
| 1970 | 247707 | 200386 | 97343 | 37873 | 8540 | 2517 | 726 |
| 1971 | 264871 | 169736 | 86163 | 34857 | 10454 | 2440 | 932 |
| 1972 | 317426 | 185535 | 81227 | 32403 | 9526 | 4229 | 1357 |
| 1973 | 407991 | 224134 | 86595 | 29644 | 9642 | 3599 | 2187 |
| 1974 | 428480 | 298642 | 111972 | 31761 | 8805 | 3679 | 2249 |
| 1975 | 318061 | 321258 | 152512 | 44981 | 10751 | 3271 | 2228 |
| 1976 | 317744 | 234216 | 158736 | 63007 | 17522 | 4136 | 2144 |
| 1977 | 450900 | 239666 | 125116 | 62069 | 21584 | 5667 | 2059 |
| 1978 | 703624 | 348711 | 144351 | 55770 | 20568 | 6651 | 2372 |
| 1979 | 583617 | 544161 | 213203 | 72403 | 22629 | 8769 | 3889 |
| 1980 | 467428 | 434521 | 325787 | 105873 | 32630 | 9583 | 5286 |
| 1981 | 632225 | 343520 | 251954 | 146972 | 40296 | 12964 | 5887 |
| 1982 | 627814 | 481182 | 211293 | 110084 | 51689 | 13328 | 6332 |
| 1983 | 449100 | 469771 | 289816 | 95703 | 38677 | 16498 | 6156 |
| 1984 | 310519 | 325787 | 277063 | 131268 | 34718 | 13965 | 8293 |
| 1985 | 257301 | 221239 | 173685 | 116076 | 44135 | 10971 | 7035 |
| 1986 | 266465 | 179512 | 117830 | 69148 | 41110 | 14407 | 5891 |
| 1987 | 300740 | 191186 | 98027 | 43608 | 20738 | 9999 | 4962 |
| 1988 | 205253 | 215130 | 100208 | 36938 | 13639 | 5769 | 4151 |
| 1989 | 122762 | 145510 | 103156 | 35066 | 12584 | 4445 | 3221 |
| 1990 | 99907 | 87553 | 64731 | 29703 | 9536 | 3949 | 2431 |
| 1991 | 90219 | 69494 | 38832 | 17122 | 6245 | 2552 | 1739 |
| 1992 | 136080 | 63768 | 27973 | 9789 | 3051 | 1307 | 889 |
| 1993 | 172474 | 100509 | 34892 | 10418 | 2655 | 784 | 559 |
| 1994 | 136080 | 129056 | 61329 | 18650 | 4293 | 1320 | 672 |
| 1995 | 120572 | 98913 | 73865 | 30699 | 7617 | 1912 | 905 |
| 1996 | 108120 | 88168 | 54557 | 32663 | 10619 | 2782 | 1005 |
| 1997 | 94466 | 79063 | 44179 | 20046 | 8062 | 3993 | 1458 |
| 1998 | 133119 | 69843 | 38254 | 15755 | 4341 | 2572 | 1749 |
| 1999 | 141775 | 99310 | 37459 | 14182 | 3526 | 1481 | 1491 |
| 2000 | 147414 | 104193 | 51175 | 13931 | 3470 | 1274 | 1091 |
| 2001 | 121662 | 104925 | 50262 | 15628 | 3380 | 1246 | 846 |
| 2002 | 119253 | 86509 | 47382 | 13710 | 3494 | 1185 | 744 |
| 2003 | 93340 | 84542 | 40864 | 13694 | 3178 | 1132 | 631 |
| 2004 | 98223 | 67643 | 38988 | 11132 | 3550 | 1104 | 613 |
| 2005 | 135673 | 72114 | 33827 | 11374 | 2531 | 813 | 397 |
| 2006 | 119970 | 102437 | 39222 | 11919 | 3154 | 793 | 381 |
| 2007 | 117243 | 90672 | 54612 | 15570 | 3558 | 1090 | 411 |
| 2008 | 126248 | 91766 | 54502 | 21584 | 5210 | 1267 | 542 |
| 2009 | 121662 | 99708 | 57011 | 25694 | 8259 | 2323 | 802 |
| 2010 | 123007 | 96375 | 63007 | 28170 | 10086 | 3620 | 1394 |
| 2011 | 133252 | 97734 | 62881 | 29614 | 10369 | 4284 | 2157 |
| 2012 | 132323 | 106511 | 60901 | 31540 | 11098 | 3363 | 2128 |
| 2013 | 164720 | 104402 | 64473 | 27806 | 12394 | 4479 | 2194 |
| 2014 | 183322 | 131926 | 66237 | 32145 | 10725 | 7051 | 3799 |