I'm not sure if the majority of people still make resolutions, but making them at the new year is probably the worst time to do so! Making a major life change after an invigorating holiday in September seems like a great idea, but trying to get better after the laziness of the festive season is plain silly. Darkness can be a great motivator, but even I get a little sick of it around January, where it is also combined with the coldest days of the year. On top of that, there is nothing close enough to generate excitement. Easter is still three months away, and spring holidays do not provide the same boost as a summer getaway.
January comes with additional frustrations in making resolutions, as everything is full with other people who had the same idea. If you wait until summer, when people are relaxing on holiday, then you get the added benefit of peace. One would have to be a crazy person to gain a new habit during the month of January.
Perhaps I am looking at this all wrong, and most people do not really want or intend to keep their resolutions, but instead see it as a way to gain some hope during the darkest and most depressing month. By trying to add a little bit of change to your days, there is a bright spot and something to dream about, at least until the sun starts shining again and spring holiday planning can begin, and plans for growth can be cast aside for another year.