How I Found Out What Is Issued For Circulation

Hello,

I have been trying to find out about what is circulated and what is not and I think I'm close but I need some help. Here is some quick background. I wanted to fill a Harris Sacagawea folder (2000 - 2004) with circulated coins. Turns out only 2000 and 2001 Sacagawea dollars were circulated. My overall question was how do you know if a coin is circulated or not? Here are my thoughts please tell me if I'm close.

CIRCULATED

1979 Lincoln Cent
P: 6,018,515,000 - over 6 billion minted
D: 4,139,357,254 - over 4 billion minted
1979 Jefferson nickel
P: 463,188,000 - over 400 million minted
D: 325,867,672 - over 300 million minted

Now, let's look at the PROOF UN-CIRCULATED numbers for the same year and denomination.

1979 Lincoln Cent
S Proof: 3,677,175 - under 4 million minted
1979 Jefferson nickel
S Proof: 3,677,175 - under 4 million minted

Finally comparing other coins that were not intended for circulation (NIFC) with Proof Numbers

1987 Kennedy half dollar
P: 2,890,758 (shown in "The Red Book" as NIFC)
D: 2,890,758 (shown in "The Red Book" as NIFC)

2002 Sacagawea dollar
P: 3,865,610 - under 4 million minted (NOT shown in "The Red
Book" as NIFC)
D: 3,732,000 - under 4 million minted (NOT shown in "The Red
Book" as NIFC)

I think I have made my point but I'm still confused as to why "The Red Book" only indicated that certain coins were NIFC instead of all that were NIFC?

Thanks to biokemist6 for helping me open my Red Book to figure this out.

I still have not had a chance to really "read" my Red Book but I reference it a lot. Has not actually reading it hurt my overall knowledge and understanding?

Thanks,
Rich