Divorce rates for those aged 50+ increased by a factor of 10…

Divorce rates for those aged 50+ increased by a factor of 109% between 1990-2015. Some have put this down to the fact that baby boomers had a very high rate of divorce and were now repeating that pattern in subsequent marriages. Of all divorces in this age range, what proportion of that total might you predict for those couples whose marriage had lasted thirty plus years?