A vertical container with base area measuring 12.3 cm by 13.7 cm is being filled with identical pieces of candy, each with a volume of 50.0 mm^3 and a mass of 0.0200 g. Assume that the volume of the empty spaces between the candies is negligible. If the height of the candies in the container increases at the rate of 0.306 cm/s, at what rate (in kg/min) does the mass of the candies in the container increase?