It may not be easy to talk about, but nearly all Americans say it's important to have a conversation with loved ones about end-of-life issues - and most have done so, albeit with substantial differences depending on age, sex and marital status.

At the high end of the spectrum, 75 percent of married women have had a serious conversation with a spouse, parent, child or other loved one about their wishes for their care at the end of their life. At the low end, just 43 percent of unmarried men have done so.

See PDF with full results, charts and tables here.

Overall, 95 percent in this ABC News/Washington Post poll think it's important to have this discussion, including 77 percent who say it's "very" important. And among those who see it as important, 84 percent say it should happen years in advance, rather than days, weeks or months.

For those who haven't had the discussion, a simple reason stands out: Many say it's simply because they don't feel it's the right time. That fits with the finding that young adults, in particular, are unlikely to have had end-of-life conversations with loved ones.

This survey, produced for ABC by Langer Research Associates, explores the subject as part of ABC's coverage of "The Conversation Project," an effort to encourage Americans to discuss their end-of-life preferences with loved ones.

Despite the sensitive nature of the subject, only 7 percent of those who haven't had such a conversation say it's because they're uncomfortable talking about it. A similarly small number, 9 percent, say it's because they don't feel they have someone to discuss it with. That compares with four in 10 who say it's not the right time. (About as many give a range of other answers.)

Seeing it as a critical issue is one factor: Among those who think it's very important, seven in 10 have had the conversation. That plummets to 26 percent of those who say it's only somewhat important or less so.

GROUPS - Women are 11 percentage points more likely than men to think discussing end-of-life issues is very important (the only meaningful difference among groups on this question) - and they're 17 percentage points more apt to have done so.

Marital status, as noted, is a factor as well. So is age: Among adults younger than age 30, just 37 percent have had an end-of-life conversation with a loved one. That jumps to 66 percent of adults age 30 and up.

Having had such a conversation also is related to education, income and race. It's 14 points more likely among Americans who've attended college vs. those who haven't gone beyond high school; 15 points more prevalent in $100,000-plus households than among people with annual incomes less than $50,000; and 12 points more common among whites than nonwhites.

METHODOLOGY - This ABC News/Washington Post poll was conducted by telephone July 5-8, 2012, among a random national sample of 1,003 adults, including landline and cell-phone-only respondents. Results have a margin of sampling error of 4 points. The survey was produced for ABC News by Langer Research Associates of New York, N.Y., with sampling, data collection and tabulation by Abt-SRBI of New York, N.Y.