What percentage of gay couples have children?

If specifically asking about marriages, see related question below.

In it's literal form, this question is very hard to answer as many couples, regardless of genders, do not develop into long term partnerships. Gay marriages have the highest percentage of households with children, at 16% in Canada. This is followed by same-sex common law unions which have about half the rate of households with children at about 8% in Canada. The percentage of non-common law, non married gay couples with children is much lower.

In the United States, about 20% of gay couples are raising children as of 2014.