In his new book Suicide of a Superpower, Pat Buchanan claims that since Vatican II, American Catholics have gotten less religious and more culturally liberal. The graph (GSS data, sample size = 13,432) shows that he's right. Attending more than weekly (gray) or weekly (pink) is down. The following are up: 2-3 times a month (magenta), once a month (gold), once a year (green), and never (red).
This graph shows that Catholics are slightly more approving of abortion for any reason than they were in the 1970s.
Trends for Mexican Americans (data not shown) are more conservative. Attendance has basically held steady over the past four decades, and support for abortion on demand has actually dropped from 38 to 23 percent. My guess is that the constant infusion of new immigrants from Mexico keeps Catholic Mex-Ams religious and comparatively conservative on abortion.