[1] 25

# A tibble: 1 × 1
  avg_weight
       <dbl>
1  0.1592457

# A tibble: 26 × 2
    year no_individuals
   <int>          <int>
1   1977            503
2   1978           1048
3   1979            719
4   1980           1415
5   1981           1472
6   1982           1978
7   1983           1673
8   1984            981
9   1985           1438
10  1986            942
# ... with 16 more rows