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Is everyone experiencing a decline in sales or just me? I want to know the general reason behind the sharp decline in sales on the site currently? There is a big difference between sales currently and the end of last year and the beginning of this year. Is there hope that sales will return this year to what they were in the past? The end of the previous year and the beginning of the current year because sales decreased significantly starting in February?

Is everyone familiar with science fiction in sales, or did I just decide to find out the general reason for inventing the passion for the site for this reason? Is there hope for sales to return to the year what it was at the previous end and the beginning of the current year, because sales increased noticeably starting from the month of February?

Content supply & demand have to align for sales to occur.

• Is there much demand for the content you're submitting?
• Is your portfolio diverse with a wide range of subjects?
• Are you using good titles, keywords & descriptions?
• Can you post the URL to your Stock portfolio?

Possible reasons:

1. Your content is seasonal.

2. Your content has a lot of competition.

3. Your titles and keywords are inadequate, such that Buyers aren't finding your assets.

4. You are not regularly uploading new content.

5. Your content is not high quality, and Buyers are choosing something else.

Yes, there is a specific reason for that: buyers are buying less of your assets.

Sales are always fluctuating. Maybe your assets are not what buyers are looking for this month. You can't make statistics on one month's sales activities. If you look at real companies, they are looking quarter per quarter and are comparing quarters from prior years. But as long as you have countable numbers of assets, there is no real chance to do meaningful compares.

As @daniellei4510 said how should we know? Does your portfolio offer seasonal material? Are you constantly uploading? How are your keywords? How is the image quality? Are the buyers looking for items in your portfolio? There are several things to condider. 

There is no way anyone here would know the answer to that. Ebb and flow, plain and simple.