Perhaps you should try some spelling variations:
decrease cooperation » defense cooperation (Expand search), decrease proliferation (Expand search), decrease migration (Expand search)
cooperation projects » cooperation project (Expand search), cooperative projects (Expand search), conservation projects (Expand search)
decrease litter » increased litter (Expand search), decrease after (Expand search), decreases liver (Expand search)
litter decrease » faster decrease (Expand search), life decrease (Expand search)
decrease on » decrease in (Expand search), decrease of (Expand search), decrease or (Expand search)
on decrease » on decreased (Expand search), of decrease (Expand search), or decrease (Expand search)

You may be able to get more results by adjusting your search query.

• Removing quotes may allow a broader search: (( decrease litter decrease cooperation projects ) OR ( decrease on decrease NOT decrease ))~.