Gaussian

float x = 0;
float posX = 0;
const float MAXINTERVAL = 5;
while (x < 1)
{
    // 1 / amount of objects on spline
    var temp = Instantiate(inst);
    temp.transform.position = new Vector3(posX, 0, 0);
    x += 1f / 11f;
    posX += MAXINTERVAL - Gaussian(3f, 0.5f, 0.25f, x);
    Debug.Log(Gaussian(28f, 0.5f, 2, x));
}

private float Gaussian(float a, float b, float c, float x)
    {
        //'a' is the height of the curve
        //'b' is the center of the curve (i.e. the highest point, if 'b' = 2, the result will be 'a' if 'x' = 2)
        //'c' is the width of the curve
        //
        //                .-.
        //               /   \
        //              /     \
        //     ___,,..-'       '-..,,___
        //
        return a * Mathf.Exp(-((Mathf.Pow((x - b), 2)) / (2 * Mathf.Pow(c, 2))));
    }