No, it only goes down for the resource mined... so if you built a StarBase with 24 Mineral Miners over an asteriod field having 144%/81%/101%, then after six turns, you would have an asteroid field with 0%/81%/101% (probably should either scrap or retrofit at this point )
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GEEK CODE V.3.12: GCS/E d-- s: a-- C++ US+ P+ L++ E--- W+++ N+ !o? K- w-- !O M++ V? PS+ PE Y+ PGP t- 5++ X R !tv-- b+++ DI++ D+ G+ e+++ h !r*-- y?
SE4 CODE: A-- Se+++* GdY $?/++ Fr! C++* Css Sf Ai Au- M+ MpN S Ss- RV Pw- Fq-- Nd Rp+ G- Mm++ Bb@ Tcp- L+