The National Association of Pastoral Renewal conducted a survey of active priests in the U.S. in 1967. 62% of the respondents favored optional celibacy. 92% favored allowing married priests and their wives to receive communion. At the 1971 convention of the National Federation of Priests' Councils, the delegates voted nine-to-one in favor of changing the law requiring celibacy. Terence Sweeney, S.J., polled the 312 American Catholic bishops on this question and 24% of the respondents favored optional celibacy. The 1985 Gallup Poll of Catholic laity found that 63% favored married priests. This and other data can be found in Joseph H. Fichter, S.J., Wives of Catholic Clergy (New York: Sheed & Ward, 1992), 172-180.
For details concerning how bishops world-wide responded to Humanae Vitae and how pastoral letters formulated by regional synods sometimes served to mitigate both the binding force and the application of Humanae Vitae, see Joseph Selling, The Reaction to Humanae Vitae, Louvain University Press, 1977 (http://www.johnwijngaards.org/synod-and-facts/selling2.asp). For details concerning the development of moral theology before and after Humanae Vitae, see John Mahoney, "The Impact of Humanae Vitae," The Making of Moral Theology, A Study of the Roman Catholic Tradition, Clarendon Press, Oxford (1989).