sales (are doing something)

"Sales" are the number of items you sell or the amount of money you make from selling things:

Sales this quarter are strong.

Sales are down this month.

Sales can be "strong" or "weak", and they can:

• increase
• decrease
• rise
• fall
• be up
• be down

(something) is steadily (changing)

To "steadily increase" means to keep increasing by the same amount, again and again. Here's an example of some steadily increasing numbers:

20 > 25 > 30 > 36 > 41 > 45

Here are some numbers that are increasing, but not steadily:

20 > 29 > 27 > 28 > 40 > 40

Numbers can also steadily decrease or fall, which means to go down little by little.

(something) has been (doing something) (since a point in time)

This is how to talk about an action that started in the past, and is still happening now:

I've been taking kickboxing classes at my neighborhood gym.

Whenever you use the word "since", you have to use the perfect form "have done":

I've known him since he was born.

We've been ranked #1 every year since 1990.

You shouldn't use the simple past tense ("knew", "were") with "since".

(something) is rising

When the number of something becomes larger, you can say that it is "rising":

The temperature is rising.

The number of people who own mobile phones is still rising by a huge number every year.