We have on average 7 eggs a day, down from 9.  I suspect the reason being the hens are out of water for extended period of time during the day.  It is too expensive to turn on the heater in the coop to keep the waterer from frozen.  May be I can look into having a heat mat or something where the waterer can be placed on top of.  We will need to purchase some ready to lay pullet this year to keep up with the demand.  If we have 3 families who constantly require eggs each week, we would need to have at least 15 hens.