Hey ss888, please see my response to ronaldoavelino above.

The lower your voting power the less value you give out.

Example;
150k SP, with 95%voting power, giving out a 50% upvote: $0.69

150k SP, 45% voting power, giving out a 50% upvote: $0.29

Thats a big difference. Try and o ly give out 1000% a day (10X 100% upvotes... 20 X 50% upvotes...) and that will keep your VP stable. Give out less and it grows back towards 100%

Did that make sense? Cheers, Welshstacker