its not about starting at 100% and dropping to 0%

right now get a minimum + an amount

min=20
min + small = chem 23%
min + normal = nonchem 35%
min + wall = waller 41%+
add 30% to each number for goods on market
so a waller gets maybe 75% plus of their unspent stock back

instead it could be

max=50
max - small 50hits= chem 47%
max - normal 250hits= nonchem 35%
max - wall 350plufluffs= waller 29%-
a flat 30% gain to market feels a bit high, id suggest putting a penalty on it based on how many special attacks a country has done recently

assume 216 base turns in 72 hours with perhaps min of 18 extra for bonuses at 234 total, 702 readiness, 100 and a bit total attacks, if the 30% was reduced by a percentage of how many hits a country was doing you could simplify it to .3% less on market per hit in last 72 hours, the only 'problem' with that is suiciders dont really need to do a lot of hits compared to warriors, and if you tried to make a formula for making ss/ps reduce it more netters who were landgrabbing before being blindsided could have been doing 25 hits a day

i wouldnt even hate the idea of modifying the chem number based on sdi to penalise getting sdi a little less

or just straight counting succesful chems at about triple the rate would drop it to 41% max, putting it no higher than an average waller of 350 defends would get currently

edited because its 20% base now not 40%