day by day
Daily. With house prices climbing day by day, I think we'll be able to sell for the price we want in a couple of months.
day by day
On each successive day, daily, as in Day by day he's getting better. Percy Bysshe Shelley used this expression, first recorded in 1362, in Adonais (1821): "fear and grief ... consume us day by day."
day by ˈday
all the time; as the days pass: Day by day she grew more confident about the job.