Relationship between the diameter and cumulative number of bodies larger than the size obtained from the observed asteroids. The orange dotted line shows the detection limit for asteroids. The red circles show the diameter range used for evaluation of the distribution slope, which indicates the asteroid population. The crosses show the excluded range. The slope changes at one kilometer, a shift that asteroids near the ecliptic plane also show. The blue and green lines show the estimated slope of asteroids in diameter ranges smaller and larger than one kilometer, respectively. The former provides a basis for comparison with that of asteroids smaller than one kilometer near the ecliptic plane. A difference between the slopes of near and far ecliptic populations indicates that the collisional evolutions were different.