75% is 75% is 75% whichever way one looks at it.
You write 300 clicks per day. Are you saying that you used to average 250~350 clicks per day but are now getting 75 per day, say 50~100?
That's a massive drop and is very noteworthy, in my sector that would be like losing $120+ per day.
Your PVs have not changed, when you write 300 clicks do you mean AdSense Page Views or actual AdSense clicks?
FWIW the last few days I have seen overall PVs drop by 30% however it is on one particular section of one specific site that has always had my lowest CTR, a very low CTR.
The overall result has been that actual clicks and earnings have stayed the same however my CTR has risen dramatically.