What does "For the year to September" mean in the following sentence? For the year to September, America’s trade deficit with China has ballooned to $305 billion, up from $276.6 billion last year.

What does the preposition "on" mean in the following sentences? Imports jumped 7.5 percent to $3.12 trillion on purchases of items from pharmaceuticals to computers, along with services such as travel. For December, exports fell 1.9 percent from the prior month, the biggest decline since early 2016, to $205.1 billion, on lower shipments of civilian aircraft, petroleum products and corn.

Which idioms have the same meaning as "keep something at bay" and "keep/hold something in check"?