There seems to be a variety of possible explanations for the difference [0] (which is common across several countries). One of them is that cultural male gender roles make seeking help a shameful thing, so males are less likely to seek assistance for suicidal thoughts [1].
[0] https://en.wikipedia.org/wiki/Gender_differences_in_suicide [1] http://link.springer.com/article/10.1007/s00406-003-0397-6#/...
[0] http://link.springer.com/article/10.1007/s00406-003-0397-6#p...
I suspect that it's significant that the number of suicides over age 75 for men has dropped in those 15 years. Either reflecting a better quality of life, or a change how men are able to find satisfaction post-career.
[1] Ok. I'm making assumptions based on "traditional" gender roles here. But given the age group in question, I feel its justified. The division between male and female roles is far more present in those over 75 than the current working generations. This will change as the population ages, and be less applicable in 20-40 more years. But it's still applicable to this group today.
For women, when their husband dies, it's almost no big deal for most of them. They just continue on with their social group, and they can live for decades.
For men, when their wife dies, they usually die very quickly after (and not usually by outright suicide either).
So far things it might be are:
1) similar levels of attempts between men and women, but with men chosing more lethal, less survivable methods
2) women talk about their emotions more and thus people spot their signs of distress earlier
3) stigma means men don't seek help
4) men just don't seek help, but not because of stigma
There's big pushes on men to get them to talk more, which is good but misses the point. There has to be some service there for them to use, and I'm not sure those services exist or are good enough. And many men are in the care of specialist mental health services when they die by suicide, so they've already asked for help.
Older people have very high rates of suicide. But it tends to be masked a bit because older people are at increased risk of death from a bunch of other causes too.
[1] http://www.who.int/gho/mental_health/suicide_rates_text/en/