Summer relative humidity 50%-55%. Winter should be lower, low enough to avoid condensation or frost on the inside of the windows. High humidity during the winter indicates a tight home that should have mechanical 50-75 cubic feet of fresh air ventilation per minute continous or at least when the home is occupied. The ventilation is needed to remove the moisture and indoor pollutants. The same amount of fresh air ventilation must be continued throughout the year to remove the indoor pollutants. This could be a heavy duty bath fan or make-up air fan if you have open combustion heating equipment. You will need additional dehumidification during the summer. If located in WI this increases heating +-$50 per year.