¿Why are the Steem Power of my publications decreasing over time?

Hello Steemit community, as you know, I have been with you for a short time. Being part of Steemit, involves falling in love with this, browsing, investigating and learning new things every day to improve our publications, and make them more pleasant to the public.

However, despite my research, there is still one thing that I do not understand, and I would be very grateful if you could instruct me about that. Why are the Steem Power of my publications, associated with the votes of those who are pleased, decreasing over time?

I'm sure you've noticed, and maybe many have the same question ..

So dear friends, if you have the answer, I would be very grateful if you would clear my doubt! ..

Thanks in advance

Alejandra