It will be hard to compile statistics for Reform or Conservative, and that assume you define Reform as being a member of an official Reform congregation. Most Jews don’t join a congregation, and no reform and most conservative involve the congregation in divorces. You also have a problem that many Reform, Conservative and “non-affiliated” persons who say they are Jews are not according to halacha. And on top of that, the less “Orthodox” you are, the more likelihood that you have a de facto marriage (which if you are childless as is common among non-Orthodox Jews) which results in not paying a “marriage penalty” in income tax. And what about the growing tendency of non-Orthodox Jews to have same-sex marriages?