Stamp Mounts For US Sheets

I have a friend who asked me if I knew of anyone who published mount sizes for new U.S. full sheets. He's primarily interested (for now) in the sizes for 2019 issues. Not knowing the answer, I thought I'd pass it on here. My inclination would be to visit U.S. postal bulletins for the entire year and collect sheet size info from that source and then figure out what mount size is a best fit for each sheet. But I suspect it's possible that one or more of the mount manufacturers already provide the info.
Added: Think I may have stumbled across an answer myself. Had searched for Scott & then Showgard mounts. Tried again & found iHobb.com … which appears to have Showgard mount sizes for 2019 sheets.

*** Moved by Staff to a more appropriate forum. ***

Global Stamps also has a cross reference of many sheets.

https://www.globalstamps.com/

For example

Recent Stamp Releases (for more see Stamp Mount Size Guide Page)

#8203;

Arnold Palmer 2020 #997 or #192

Art of Magic Plate Block #1140

Bioluminescent Life #188

Dragons #1190 or #1034

Ellsworth Kelly #181

First Moon Landing (2019) #215

Hanukkah #1009

John Lennon #1001 or #181

Lena Horne #216

Little Mo #1168

Lunar New Year #151

Marvin Gaye #181 or #1007

O'Beautiful #997 or #192

Post Office Murals #188

Sally Ride #207

Sesame Street #135

Spooky Silhouettes #1025

State County Fairs #215

STEM Education #1168

Transcontinental RR 2019 #1003

TRex #181

USS Missouri #1002

Whitman #151

Wild/Scenic Rivers #163

Woodstock #1043

#8203;

Al ... thanks for the info. My friend Russell uses Scott mounts rather than Showgard, so your global link is likely to be more useful to him than my iHobb link.
John

You can just use a plastic sleeve sheet (Avery, Wilson Jones, etc.) from most retail stores.