Unfortunately, English is notoriously ambiguous when it comes to terms around time. There is no one word that encompasses both of these definitions, and the only short phrase I can think of is "up to and including". Example:
The country was stable up to and including most of 2018, but a series of public scandals in the summer of that year rocked faith in the government, plunging the entire country into chaos.
Almost every other term, such as until or up to is still ambiguous, as it does not specify how much of the event took place within the given year. You'd have to add more information to be specific. For example:
Until 2018 the singer was relatively unknown, but a hit Christmas single in 2017 pushed her into the spotlight, and soon it seemed everyone knew her name.
In this example the exact timing of the singer's fame is ambiguous, and indeed, unimportant. The point is that, more or less, she was not famous in 2017, and was famous in 2018.
That being said, you can add the word "inclusive" to a statement to mean "including the start and end points of the set". Example:
The test gave us one minute to add up the numbers between 1 and 100, inclusive.
However, this term is mostly used in things like science and mathematics, and can sound a little strange in casual conversation, or with dates. Unless of course, the conversation or the dates is about some kind of mathematics.
The revenue for the company from 2010 to 2015, inclusive, was only a fraction of what it made in 2016.